Check this out! Daily newsletter deal on a newegg Sapphire Radeon 6850:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102908&nm_mc=EMC-IGNEFL011012&cm_mmc=EMC-IGNEFL011012-_-EMC-011012-Index-_-DesktopGraphicsVideoCards-_-14102908-L07AThat means you can use Sapphire Trixx to OC is REALLY easily.
Use the code: EMCNJJN45
and it's $15 off! That brings it down to $135 with free shipping. Now I don't feel so bad about the lack of 5830's because this is very comparable cost-wise and electricity usage-wise. Those start out at about 213 MH/s (and the 5830's start at 286 and OC easily to 310-320 in most cases). I know I'm getting at least one :-) I don't think this is better than a practically identical but cheaper 5770 though, which they have one from MSI for $115 so do consider that.