i tend to buy brand boards over shop boards just because my local shop only has one graphic and ive skated it out sooo many times, however those kids are idiots...
if anything buying a shop board is the best thing you can do, skate shops are meant to be a give and take situation where they support the skate community by holding contests and jams and signings and all that jazz, and in return we help keep the shop alive by buying their products.
it is better for your skate community to buy a shop board than to get a branded board on sale for the same price