I don't recall seeing anything on the CanBe version, but there doesn't seem to be much demand for either of the other two. The PC-98 version is seen more often, sitting on ebay unsold for $100 or going for even less on yahoo auctions, and the somewhat less common DOS version fetches a bit more.
Unfortunately (or fortunately), the poor PC-FX doesn't have much "collector" appeal.
The PC-FXGA98 has at-least some appeal in Japan, where there are still a lot of PC98 fans ... but it has little purpose over here. You might try on nfgames.com where there's a PC98 forum.
The PC-FXGA DOS/V has little appeal in Japan, except for its rarity, but makes a little more sense in the Western world where there are still
some people with old ISA-bus machines for running really old software.
The problem in the Western world is the nobody gives-a-damn about the PC-FX except for a few particularly demented weirdos here on this forum (like me).
The FX98-IF is definitely a rare toy ... and sorry, I have no clue where you'd go to get a decent price on that, but once again, you could try the PC98 guys on nfgames.com
I wouldn't object to having a spare PC-FXGA DOS/V (just-in-case) so I'll get in touch by PM.