$150 is for a single set, if we get 5, i would split the cost out, so it would only go down from there.
this would be for the adapter plate only, then you can get mk2/mk3/corrado rear brakes and bolt them on.
if you wanted fancy, and new you could get this and bolt it on:
Audi and Volkswagen Eurospec OE Design Performance Brake Kits
scroll to part #EBK 698 226 A2-A3-4R thats the rest of the conversion "brand new"
or you go to a pull it yard, shop craigslist for part outs, or look on vw sites, and find the whole conversion needing new pads and rotors for @ $50.. i paid $40 for my set up.
you would still need to hook up the brake line and e brake, but thats not too too hard.