What is this, Antiques Roadshow?
You're sitting on a gold mine, OK? Whether you sell it as a whole, the Frankenstein 4000 that you've made, or whether you sell the individual parts, either way it is worth a lot, certainly more than most computers from the early '90s.
Like one of the other posters said, it's worth what someone is prepared to pay for it. And Rabbi my amigan friend, there are people out there that are prepared to pay ridiculous amounts of money for what you have. Price/MHz, Classic Amigas are almost unbeatable.