Heck no, don't be foolish and buy new. There are lots of punters out there who upgrade to the latest and greatest every 2-3 years, so just grab their cast-offs for 1/10 the new cost.

The pay-off for your ultra-cheap electric bill may still be in the 2-3 year range, but you'll be doing the planet a favour too, as well as saving some (tiny) hidden costs on the air-conditioning bill as well.

Cheers