I would give Hybrid Connection or Innovative Tuning a call with your requirements. They can probably help you out with your needs. I know the parts except the turbos themselves will be very easy to come by.
couplers you can get at home depot or lowe’s :lol: , thats where i got my 2.5" ones, then for 3" i got them at pep boys. mandrel bends i got on ebay, intercooler i got on ebay, turbo i got from CTSturbo.com(brand new), BOV i got a 1g from hybrid, and wastegate off ebay. just start shoppin man. get the big stuff online when you find the best deal, and get the smaller stuff local. hell i even bought a hydraulic line from carquest for $15 rated for 1500psi to use as my oil feed line.
We can get you everything on that list except the turbos, which a junkyard could help you out with. Are you looking for straight or U bends or U-J bends or what on the piping?