How much would you pay for a really good Python only IDE? TextMate is about 60 bucks and was nice as a text editor but I thought it was lacking too much as a total package, but it can parse a whole lot of different languages so that justify its price tag I thought.
Ideally I want a package that is easy to use, gives me flow control <grouping and debugging>, allows me to search for anything, flag the number of times a variable is used, fast text completion <sub one second>, create modules, and finally integrate into a local compiler and let me work with Cython out of box - even select a module and convert it to Cython if at all possible.
Maybe even offer virtual modules so you can author a blender module outside of blender using this IDE and once it works the way you like, test it in blender. Because lets face it, blender is a 3D package with a text editor built in - not an IDE.