Where is it cheaper? Consider return policies. Are they still under warranty? There are a few things to think about when purchasing at different places. Personally, I'd prefer a new one, but that's just me. I'm not to fond of refurbished items.
I scored I great **** deal on a refurbished mpc1000 once. After a year the lights went out on that one. No warranty nothing. So that made me figure, if I invest that amount of money in a machine, I want to be able to use it for at least 10 years (hence the mpc60's and 3000's). It will save money in the long run to buy an mpc that hasn't been beaten to death and that also give some guarantee some defects can be fixed without costing money.