I have recently installed a XFX XXX edition 5830 in a PC for a friend. Going from a 4850 it made sense here in the UK to get a £84 5830 over a higher priced 5770. The 5850 was the card of choice but my friend couldn't justify the extra price when looking at benchmarks in reviews.
I bet he is gutted now i just today received E-mail from a retailer selling teh 5850 for £99. Still you wont get anywhere if you sit and wait all the time. She was very happy with the 5830 anyway.