Preface: (read if you want to know stuff NOT concerning this guide, otherwise skip)
this guide is to let you guys find out how to use ebay to it's fullest to get good deals and to get those hard to find items, i don't do this anymore since it's a bit involved, but when you want to find that illusive item, it's worth it. Couple of things, i'm trying to just help you guys, chime in if i miss anything, this guide is written with the geek in mind, if you can't make an ebay account i really can't help you, the reason to use ebay is cuz the whole world uses ebay, other than flee markets, where else are we gonna find keyboards?
1. Log into
Ebay (i'm assuming you know how to make an account and already have one)
2. start searching

3. this is your normal ebay screen, we'll uncover a few gems to make us advanced users
4. start typing in what you want to search, we'll try the old model m first

These are keywords, basically in all of search engine world, it boils down to typing in words that the search engine can find and give back results, make note of all the results being generated underneath your search, these are ebay suggestions, much like google suggestions, tho these are going to be more related to the subject matter at hand because it deals with the ebay/buyer side of things than google would (not that we won't be using google)
5.

ok keep in mind that you now have related searches as a clickable link, so if you want just click those links also, if you want to stay on the same page, hold down "CTRL" and click and it should open it in a new tab so you don't loose your place.
see that star where it says save, this is where you become 99% better than the rest of the people using ebay, click it and you get.

so now you'll get emails when ppl post up new(please don't reply with "i already knew that" a lot don't and if you reply with that and just that alone, i'll campaign against you!)
6. of course you can narrow down your search more, like you only want free shipping, a new/used item, blah blah

7. Now that we know how to get ebay to us results directly to our email, how do we find more keywords. cuz as you've seen ebay only gives you a few related results, we use google. Get a google account, it's free and you get one anyway when you get a gmail account, most ppl have one, you should get one. then type in google.com/adwords, Don't worry we won't be spending any money on here, we're just using the free tool called "google keywords tool" (iyou can use it without an account by going here
https://adwords.google.com/o/KeywordTool but you might be limited on the amount of results and you have to enter in a captcha per result)

now see all these varied results, don't make sense, click where it says only show ideas closely related and you get
8.

there we go! lots of related keywords for us to use, plug into ebay and have ebay mail back to us the results.
9. why do we need so many keywords? well not everyone calling a model m, calls it a model m. Someone might call it a model m clicky, or just a 1390131, you need to have all variations, to "catch all the results". Why? it's like fishing, why fish with one pole when you can fish with 10!, you're bound to get more results and more hits. Also the more you get the chances you have of finding the lucky one that almost no one bids on, that's how these golden nuggets are found, sure everyone can seach for "ibm model m" and you'll get lots of results for a model m that bids for 40, but if you're the only one that searched for "ibm clicky keyboard" and no one has found it
advanced knowledge:
now sometimes you want to see how "popular" the item is, how many ppl have looked at the item? well only the seller chooses to show you this number, at the very bottom... but i'll show you how to find out this and more
you also might want to know how many ppl have "watched" this item, that means ppl are looking to bid on this item, you basically want to know if you have competition or not, i'll show you!
1. if you have the item you want to know all the hidden info on, goto your url bar, find the number code, it's gonna be different for every item, but the position of it in the url is always the same

then goto
watchcount.com
put in that number into the keyword search and bam

look at all that delicious hidden info that we've uncovered, trust me this is valuable stuff.
now that's all great and all but how about bidding?
advanced bidding:
esnipe

ok so we've heard about this "sniping" thing what is it and how can it save me money? basically in short, it's a program or a server monitor, that will bid for you at the very last possible second. What does this try to discourage? it trys to discourage bidding wars and quite honestly lets you live a life, you don't have to sit at your computer at the oddest hours hoping to win a bid, cuz quite honestly a lot of the times, it comes down to the last few minutes to see who wins and who looses.
with this i've used esnipe, why? well i've used them there are others, so you can research for yourself, i'll just say my experiences with esnipe. They are server based so there's nothing to load on your pc, this might mean that some people don't want their pc on 24/7, that's a plus, it also means that esnipe has a boatload of servers with probably a better internet connection to bid for you than if you used some program to bid with. they only take a fee if you win, so this means you could bid for 10 items, win only 1, and have esnipe take only that one bid's fee. they have reasonable fee's, basically they take 1percent of the winning bid, so if you won a $100 keyboard you'd pay $1 for the service, which in theory could have saved you a lot more money than if you didn't use the service, there's a few more with the fee's like 10bucks is the max fee and stuff like that you can read all the rules on their site.
Ebay Issues:
Low/No Feedback- just registered for ebay? never bought/sold on ebay? but now you want to purchase your dream item but the seller won't accept anyone with a low/no feedback score? Depending on how much you want to spend for feedback, yes you are buying feedback.
1. pick a category, gifts/games anything small
2. goto advanced search
3. click on buy it now
4. click on free shipping
5. sort low to high+shipping
6. you'll see "whatever" for .99, buy from different ppl, basically if you want 10 feedback 100% spend 9.89, after you purchased, immediate give the seller feedback "A+++++++ SELLER SUPERFAST" or any traditional stupid ebay response, you're just trying to elicite the same feedback score, and 9 times out of 10 they do it, cuz that's how the game is played, sellers will happyily give good return feedback, especially since you already paid. (heck if you don't even get the item, the feedback score is more important, it's only a buck, and you probably didn't even want the .99 item anyway, remember you're just buying feedback)
Is this unethical? yes and no, you're gaming the way in which ppl are judging their buying/selling experiences, but then the score itself is treated like a commodity (sellers with less than 97% positive feedback do not last, and just end up making a new account anyway), so it's not really an opinion but rather a bought vote.
Don't use this for evil!