I am using a x0xb0x for some time now...one of the best (if not the best) 303 clones available.
You can make your own kit...or buy one....and is even editable with customised firmware.
Check :
http://www.ladyada.net/make/x0xb0x/
or
http://www.acidvoice.com/index.htm
Here is how mine x0xb0x looks :
