Just an addition to my previous post. Those m-audio controllers will only work if you are setting up via a computer as they only have USB MIDI interfaces not MIDI din sockets like the TX81Z. If you are looking to use it live then you need to get any MIDI keyboard with din sockets. There are plenty of cheap keyboards around that use standard MIDI plugs. Most of the real cheap Yamaha PSR and Casio keyboards have standard MIDI sockets.
[This message has been edited by Nigel (edited 12-29-2007).]