If I hadn't bought a used SP-404 (underwhelming, IMO) I'd take a serious look at Akai's new offering:
the MPX8SD sample playback unit. As far as I can tell it has no effects and doesn't even have any onboard sampling abilities, but you can load samples via SD card and play them back on the unit's 8 velocity/pressure sensitive pads, it has MIDI and it's cheap! Definitely check this out.