Afraid I have not really paid much attention to the neogeo flash cart and mod market in recent times, give or take things like
ebay does indeed dislike flash carts and I would not suggest the end runs that people use for more popular systems like the GBA and DS.
GBAtemp's own trading section is limited to those with more than 100 posts outside the edge of forum/introductions and advertising outside there does not go down well. If someone sees your post or your signature however and subsequently PMs you then that is on them. No idea how many people would be actively looking or "ooh I would like" for such a device on GBAtemp but pick an older/rarer console and you can usually get a conversation about it going on around here (and when various emulators appeared on consoles we deal more often with for the various neo geo devices it appeared there were some fairly knowledgeable people among the regulars).
Looking around there is http://www.arcade-projects.com/foru...ridge-new-poll-included-please-vote/&pageNo=1
set to appear before too long (AES and MVS supporting no less). Such a thing might change what yours might be worth -- a lot of these old devices did not have great flash carts and most that were around were quite rare and hard to come by legacy devices or clones of them/designs based upon them, in many other systems people like http://shop.krikzz.com/
came along with new designs using modern electronics and completely rocked the market.
might be worth a look around.
This is not my world though so I have no idea on prices you can expect, and I would hate to suggest a few rounds and shipping price (if it works you will almost always be able to get someone to part with a token sum and shipping) when it would have actually started a bidding war.