It depends on what you call affordable... the prices have come down drastically on the whole of the Akai range shop around you should be able to pick something fairly decent up for less than £500, but remember you might need an external effects unit as well... if money is really tight get a SBLive, or even two and use the APS drivers on one.... on a 256MB PC this would give you 160mb sample RAM and effects 64 midi channels and 32 external midi channels.