I looked at 5750's specs by mistake, sorry

so a 4870 is about 1.2 tflop, 4890 about 1.36 tflop, 5750 is 1 tflop and 5770 again 1.36.

Still it should be memory bottlenecked and when AF kicks in I doubt it'll perform anywhere near 4890.

About 4890 best case, about 4850 worst case: $160
About 4890 best case, about 4890 worst case: $185

Only, the former consumes less power, is DX11. This isn't what you get for a product that's newer by one year