What do you planning on doing with it?
I never used a 303, but had the 202 for a week or so when it first came out and found it very limited, so I returned it. Sampling time is limited, pads and sequencer are basically useless. FX are just okay.
It doesn’t seem like the 303 is a huge upgrade (just better FX and more sampling time) and for the price there are probably much better options out there.