they point still everyone seems to forget is the power consumption
ok your 3 shiny R290 costs only 2400$ but they eat what... 1kW?
so thats 3-4 gpu rigs you can run even on a european power line
then you need mobo, cpu, ram, fans, fizzle around with os and config
and risers. cuz you just cant run these in quad-sli placement for 24/7
for all that stuff you then need that open frame case or an ugly crate
these usb miners might be expensive at launch, but they will come down
but first someone needs to take the first step and fund further development
then you will get cheaper chips and larger miners with better kh/price
like the ratio of block erupter sticks was against their blade counterparts
3x r9 290 is more like 1250 $ USD
Nice try ...
Plus if something happens, try to sell that to gamers.
Good luck.