Depends on whether or not you are a cheap bastard like me.
I use a $20 (Australian) aqarium pump that I got off e-bay. Its all food grade/magnetic drive, so its safe for the beer, and while I thought that boiling wort would probably melt it into a blob, it didn't do a thing to it. I even circulated boiling water through my whole system to CIP for an hour or so and no problems at all. Besides, new impellers etc only cost a couple of bucks even if you melt one.
Had to use a rubber stopper to connect on the intake, but you could muck about with plumbing fittings to get something a bit more permanent if you wanted.
Heres a pic
The major disadvantage is that it deosn't self prime very well (at all) so if you are syphoning instead of using a spigot, it takes a little bit to get it started.
Not for every one, but seems to work ok and was really cheap.
