I was the eBay seller of Typoman back in May. I have to admit that I was as surprised as anyone that it sold for as much as it did... I picked it up for $2 at a thrift store (along with a ton of other games). I generally only sell/trade my duplicate copies, but after a year of checking out TI-99 carts on eBay, I never saw another one listed. Judging by the bidding action, I assume others hadn't seen them either.
Used the money to buy a ton of other classic console games that I was missing!