This site is mostly just an unofficial and incomplete collection of INCA manuals. I do not buy or sell INCA machines.
If you are looking to sell your INCA machine to someone who appreciates it. Go to the incawoodworking yahoo group. Its got 1600+ INCA users/owners. They'll give you a fair price. You have to register to view or post messages there, but its worth it.
Alternatively, put your INCA machine up for sale on ebay. Then post a link to it on the incawoodworking yahoo group, so the people there have a chance to bid on it. Don't forget to mention your location.
There was a small poll on the inca woodworking forum about "the polite and proper way to post a sales offer".
Most all prefer the Craigslist-Style over the eBay-style. So its probably best to follow their preferences when posting there. "State the desired sale price and sell to the first responder who agrees to said price."