Does anyone have a rig or just the cards for sale that get around 1 ghash/s for something like $500? Is that a lowball or fair price or expensive as shit?
Depends on the hardware. For most video cards, that's a little low; for a low-end ASIC processor, it's actually a little high. Consider the "Bitforce Jalapeno" from Butterfly Labs, which they just upgraded to $250 each, and is about 5GHash/s ... for $500 you could buy 2 of them, if you're willing to wait the 3-4 months for shipping.
But you could also buy a decent computer which would give you a more immediate solution, with less computing power. The tradeoff isn't just the time, it's also the fact that when it's outdated, the computer is still very much operational and could make some third-world kids very popular in their village.
So let me know, in any case, if you have further questions.