Well im certainly not gona give them away if thats what you all want just cause you compare them to 5830. There both fairly high-end cards for gaming. 36btc is not much to ask.
The price is more reasonable.
You should sell them separate. You've got a high end 69xx card, a high end 58xx card, and a low end card. It's a weird setup. People usually match them I'm not sure who is going to want all 3.
People like to go all 6xxx series, all 5xxx series, all high end or all low end. Who is going to buy a mobo, psu, ram, cpu to toss these 3 cards in? They are people looking for the 6970, there are people looking for the 5870, a few people would buy the 5770, but no one is looking to buy all 3 at once IMHO.
They'd sell much more quickly on their own. Good luck!