If you are on a budget, get the Behringer Truth 2031a's. They are flat and accurate for their price range. Don't let the Behringer name scare you. They are only about $199 each here in the U.S.
If you have a little more money to spend, get a pair of Yamaha HS80m's. They are $299 apiece in the U.S. and are very accurate. Whatever you mix on those will translate well to other sources, like home stereos, car stereos, ipods, etc. Stay away from monitors that will color your sound, because when you listen to what you've done on another source, it won't sound like what you expect. If you make your mix sound good on the HS80m's, they will sound good anywhere. They are also quite powerful.
MPC 1000 w/ JJOS - Korg ESX - Korg EA-1 - Ensoniq EPS 16+ - Waldorf MicroQ - Roland Alpha Juno 2 - Yamaha TX81z - Mackie CR1604 - random rackmount and pedal effects