Ruby

I bought the professional version of Komodo 4, the multi-language Web-Dev IDE. I bought the personal version of 3.5 and actually started using it, so I decided to buy the professional version of 4 while ActiveState was offering me a big discount. I'm happy with it, but I spent a few hundred dollars on it before I realized this:

the Gui builder toolkit (previously present only in the pro version) has been removed from pro 4... and is now available for free here.