If it's work related do you actually need a mid-range PCI-Express card? Why not go with a more basic solution?
If you do need some level of performance then yes, the X800*, X1600* and 6600* cards is where you'll end up if you don't want to supply additional power to the card. And I understand your concern, especially if you're working with a boxed PC with some generic 250W power supply.
I'm running a Sapphire X1600XT at the moment. I'm an occassional gamer and wanted a card below $200CDN w/ SM3.0 support... enter the X1600XT. The AVIVO features also appealed to me as I do a little video work from time to time. As for performance, it's tricky. The X1600XT beats out the X800/X800GT, will run with the X800GTO and frequently beats out the 6600GT. Yes, there are some titles where the 6600GT will take the lead, but that's usually in pure speed benchmarks... the X1600XT will usually jump ahead once the eye candy is turned up.
Anyway, there are options... no need to have the latest/greatest and sometimes we can't wait for the next model to be released.