My first computer was a 80286 bought in the summer of 1986 with a Model M. I used that until the mid-late 1990s and got a Dell system with an AT101W, which I used until the early-2000s when I got a Compaq with an SK-2800 "internet keyboard" (excellent rubber domes with "rubbery" media keys).
A few years later I built a computer from parts and realized that the 2800 felt much better than the other keyboards floating around. Also, rather than selling off the system, I handed it down to my daughter, so I did not have to give up the keyboard that I liked. Eventually, I got a couple more 2800s for little or nothing as backups.
In 2010, I was posted out of state for a few months and only had my personal Acer laptop (along with another laptop issued for work) and I was dying over the horribleness of the laptop keyboards that I was stuck with.
During that time, I idly searched "best keyboards" or some such on Google and was very surprised to find an entire subculture there.
Returning home, over a few weeks and months, I looked in on various salvage and 2nd-hand stores, and retrieved the AT101W (which I had sold to an acquaintance who still had it in a closet). I picked up some junk but nothing good.
Then I found a filthy Northgate Ultra for a couple of dollars but it had a few dead keys (today, I would have harvested some of the Alps from the Dell and had it up and running in an hour). I corresponded with Bob Tibbetts and asked him about repairing it but ended up selling it to him as-is for about $30. It was not one of the desirable 101s, it had a bigass Enter and no upper row of function keys.
By then I had gleaned that the Model F was the thing to have, but ATs were at least as rare and expensive as they are today, but XTs were dirt cheap (before Soarer came along). So I got one and coughed up the $50-$60 for a first-generation Hagstrom and felt nirvana. But the layout was an abomination so I sold the rig as a set, with the Hagstrom mounted in a plastic "Tupperware" style box. This was about the time that I had started on Geekhack, and Ripster found the ebay listing and scoffed at it as "ghetto" but I got the last laugh when I sold it (for over $100 and a small profit) to a California Apple employee to hook up to his early iPhone!
With that I got a proper Model M and started down the rabbit hole. I have still only bought a couple of keyboards brand new, but a number of good used ones on ebay and here. Since Soarer published the converter, I have been mostly focused on Model Fs. I got started there when I bought 3 horrible broken filthy incomplete F-122s in a cardboard box from Rawko (near my office) for $85 and was able to build 2 working ones out of it.
I have picked up a number of cheap-o junk keyboards in thrift stores and salvage shops, many quite interesting, but nothing of outstanding importance. In the last few years, that has become much harder. 3-4 years ago Apples and AT101s were not uncommon, but I have not seen one of either in well over a year now.