I was just wondering how do those keyboards worth*:
-Dell AT101W
-IBM Model M
-IBM Model M space saving (M mini should I say*?)
There are a lot of variables to consider when pricing vintage boards, and the price you'll pay on eBay or through a collector will likely be considerably more than what you'll see at a local thrift shop, pawn shop, or a through regular Joe on Craigslist. Location also plays a big role.
Now, with that out of the way... I paid fifty cents for each of my ten AT101Ws at a local computer shop ($5 for 10), and $20 each for my Ms. My Northgate Omnikey 102 and 101 ran me seventy cents and one dollar (respectively) at local thrift stores. In total, I've spent a bit over $60 total on all of my keyboards, not including restoration costs or all the gas it took to track them down.
On eBay, I'd say maybe $15-$30 is fair for a standard used AT101W in good condition, and $30-$50 for a run-of-the-mill Model M.
I should mention that I'm a noob, so it's probably best to take any of my advice with a grain of salt.