I've seen confirmation of £160 ish and a release date of 29th June in the UK.
280x cards
with an overclock the 480 can probably do 28 mhs with 150 watts oc which is a bit better power wise than a 390
but not worth the upgrade
then the 1070 is vastly better because it can do 37MH at peak with less than 150w, and 32MH stable
no other gpu can even dream to come close to this perf per watt, the only downside is that you need linux for this...
If the 480 can only do 24 MH/s at 100W, It is difficult to do 36 at 150W. Then 1070 wins if that can do 37 MH/s at 150W.
yes it can do that but on linux only, waiting for new windows drivers fix to have better hash there