Since you are using the keys for production, not live playing, I wouldn't suggest spending extra money. Something like this; http://www.m-audio.com/products/en_us/Oxygen49.html
(Easy budget MIDI controller, faders/knobs for effects, modulation, active octave changing, weighted keys)
Would suit you just fine in a DAW of your choice (Fruity Loops I hope).
You don't need extra keys when you're going to have to map the notes out afterwards anyways, and you can do active octave changing if you need to go up or down.
Hope you find what you're looking for!