Allison2, I know it may be pushing your budget, but for $650 you can get a Shelter 501 MkII, which is a substantially better cartridge than any of the ones listed above, and indeed competes with cartridges costing $2-3k. If that is a little too far out of your budget, the Denon DL-103 or DL-103 Pro is a good second choice.
Best all-around cartridge for 500.00 new
I just purchased a Rega P25/RB600 and am shopping for a worthy cartridge. I listen to almost anything and spread my listening time among most genres about evenly. I've only got a few dollars left to spend and want to get the best all-around cartridge available. Any thoughts on the Grado Sonata or am I just asking for trouble with hum?