The comparison isn't even remotely valid. 780 and R9 290 are pretty close in power usage and performance, but R9 290 undercuts it by $100.
480 used
nearly twice the power of the 5870 in games and 480 cost $140.
5870 = 143W vs. 480 = 272W (+90% more!)
780 = 222W vs. R9 290 = 245W (+10% more)
As far as noise and temperatures, everyone here knows AMD's reference cooler is junk, which is why a lot of people will just grab after-market R9 290s instead.
Ok but a 4000 SP GPU would be 35-40% faster than 780. Of course AMD would charge more than the 780.
There is a fundamental difference between ATi/AMD and NV. When ATI/AMD are in the lead, they do not start overcharging by ridiculous amounts (9700Pro, 5870, 7970). When NV is in the lead, they do (8800GTX Ultra, GTX280, Titan).
If you look at NV's loyal supporters, they just keep buying NV, regardless of price. AMD's loyal supporters are not supporters of AMD, but of price/performance. That's the fundamental difference. If NV became a leader in price/performance, AMD users would switch in no time. For a long-time NV user, even if AMD undercuts NV and beats them, there is a high chance they still won't switch. Because of this, NV prices their cards however they want until the point where they prices just look ridiculous and they drop them to save face.