I hope you don't consider this a rude reply, but you asked the question and I think this will be the general consensus:
$400 is an outrageously high price. But, its well known that if you post rare stuff on ebay at a very high price, there's a chance that someone for whom money is no object will decide they want it when they want it, and they will pay that price. Look around and you'll see sellers that do this with tons of games, reposted every time the auction goes unbought, hoping for that chance. And they do it because like I said, it works. You just don't get to decide when (or if) it sells.
If you want to control when it sells, your only option is to list it as an auction, publicize it as well as you are able, and see what the going price is.
A boxed copy went at auction for just above $200 recently, and a loose cart got no bids at $99. I doubt that this was a case of something valuable slipping under the radar. Its more likely that this is the current value for these games. Quite a good return on what they were bought for, but your fortune is in another castle.
PS. Financial difficulties suck. I hope your game sells as listed and your other avenues of recourse are fruitful.