i agree with the price, i would think the rear 2pots would work better, but how much better?if you want brand new, 1stsubaruparts.com is one of the cheaper OEM site.
Theres a thread somewhere around here with all the part numbers for em.
I think for a full all around set the cost is ~1200 i believe.
for rears you'll have to get the 2 pot adapter as well, runs ~200 for both sides.
ive heard the 4pots up front and H6 in the rear is a good balance and comparatively cheap.