Everybody needs a 303.
I would love an Abstrakt Instruments Avalon, but man what a ticket! Plus they're never in stock, and the secondary market on them is a bloody mess.
I think even though it is a little tiny bit raspy in comparison, that for the best bang for your buck the little Behringer TD-3 is fairly impressive, and for just a little bit more you can get the TD-3-MO which so incredibly different from the original, cloning the classic devilfish mod, that it is entirely in form a completely different instrument altogether, a complete sonic universe of its own.
So if you're willing to deviate, why not something like the moog minitaur. That is cute and has a real phatty sound, but is it acid? What is it?
Erica synths has a nice gritty beast, but honestly, I'm with fatboy slim on this one that everyone needs a 303. What he means is not a clone or reimagining of the classic, but a lovingly cared for actual roland 303, which is an entirely different statement of purpose really, if you think about it.