I've been going through the same process myself and haven't yet made a firm decision - tho Bilsteins and Dobinson coils with Whiteline bushes seems to be the best bet.
Had quotes from 1500 for ironman crap all the way up to 3200 from Ultimate suspension... which seemed way over the top to me.
I've been told to take care as even at 2" the new ST-X can have castor problems