$700 maybe just in turbos and piping. you also need BOVs, fmu, injectors, intercooler, mass air recalabrated... I got my single setup, using a big holset , I think its a hx50, I paid $350 for new in the box (a real steal), and about $500 to have the crossover and downpipe made. then its at least $400 for injectors (60#)$300 for a fuel pump, $425 for cell with the external pickup for the pump $200 for rails, $200+ for rails and $200 + for the 1/2 lines and fittings, $100 for the oil filter relocate kit+ fittings , and about $700 or more to program the ecu, or stand alone to make it work. etc...you don't need all that stuff, but if you really want to make power and want it to last I'd suggest doing it right the first time, especially to prevent detonation
I'll get you some pics of mine with the one turbo setup its would be much eaiser to build yourself than 2.