This is not intended to to be discouraging or "sour grapes" but I have sold half a dozen bolt-modded Ms and only gotten a "good" price for a couple of them.
As much of a cult exists around the "one true keyboard" it is quite surprising to me that people are unwilling to pay a premium of just a few tens of dollars for a clean, tested, complete, and dramatically improved Model M vs the crapshoot of buying a used one on ebay.
If you want the fun and enjoyment of doing it yourself, then scrounge around for a bargain basement price on a dirty original.
But if you do not have the time, tools, and/or energy for this (annoying, fussy, and tedious) project, you should spring for a couple of extra $20 bills over and above going rate for a used M and buy something like this that is really good.