I would suggest that you check out Novation's XioSynth. It comes in a 49 key version which should give you a little more keyboard space. The XioSynth has been superseded by the UltraNova but look around and you can probably still find a retailer selling a new one (49 key) for $399. It can be had for even less in the used marketplace.

Here are some features:

-25 or 49 full-size key versions.
-Built-in 3 oscillator virtual analog synth with 200 sounds.
-Built-in effects and arpeggiator.
-X/Y pad in addition to the pitch/mod joystick.
-Serves as a USB midi/audio interface.
-XLR mic input w/phantom power.
-Can be used as a software controller.
-Can be battery powered in addition to USB and AC power.

Hope this helps some. Take care and have a great day!

EDIT: disregard the info above as I didn't notice your comment about needing 61 keys or more. Five octave synth/controllers with built audio interfaces are a hard find as controller manufacturers seem to prefer more compact sizes. I think Roland, Yamaha and Korg are now including interfaces on their synths but they are likely to be priced beyond your budget. Check out the Akai MPK range. They have a 61 note version. No built-in sounds, battery power, audio interface or effects but still solidly built, have Akai drum pads and make excellent software controllers.