Between our family and my sisters family, we have a total of 7 IKs, 2 double lynxs with air floors, 1 double lynx with foam floor, 3 single lynxs (all air floors) and 1 single strike (air floor obviously). We have got these all used and in excellent to very good shape, I give the list below as examples for comparison and all of these were found through craigslist in OR and WA:
lynx II foam floor very good shape that also came with a very spendy AT paddle for $550 several years ago (my main multiday IK boat for larger rivers where horse packing is not involved and generally sub class IV, put a new minicell foam floor in it this year for $120, FYI minicell is way better than the stock foam Aire used originoally, minicell can't ever suck up any water, the minicell cuts/shapes very will with a saws-all with metal hacksaw blade)
lynx II air floor excellent shape came with boat bag, 2 sets thigh straps foot pegs and cheetah chairs for $600 got a few years ago, brothers multiday
lynx II newer style air floor, essentially new $700 got this year, sisters for multiday
two lynx Is with cheetah chairs, and thigh straps from silent auction at a univeristy outdoor program in good shape $327 each (actually we got 3 for this price, kept 2 and had a friend pick 1 up) got this year, used all three of them on the upper Chetco Hell Yes!, and currently using them for work on some river surveys this fall.
mid 1990s lynx I with new cheetah chair, thigh straps, and foot pegs, and a nice 210 older werner paddle for $600 the boat was essentially new and maybe in the water 5 or six times. Before I saw the boat, I was thinking no way I am going to pay $600 for a 1990s lynx, but when I saw it, it was in such new condition, I didn't even haggle (and if you knew me, that would be a rare event), got several years ago, my wifes IK
strike I, pretty much new, with thigh straps and foam foot block $550, got a few years ago, my sisters IK
The point of this post is to illustrate our experience finding good used IKs for good deals, they can be found!, at least we haven't had too much trouble building an IK navy, good luck
ps, I have paddle a fair number of different IKs and think all in all the older style Lynx I is pretty much the best all around IK for anything you can get, if you could only get 1 boat. Handles class IV+ creeking nicely, larger water well, hold a fair amount of gear for self support over nights, hold a pretty heavy load all things considered.