Consider this market they are in. PinkPerry's in L.A....warm weather, a healthy alternative to traditional yogurt, plus packed with nuts and fresh fruits... those L.A folks don't mind paying $5 bucks for that.
People thought it was funny when Starbucks wanted to charge...HOW MUCH for a cup of coffee? Now look at them. Then others poked fun charging HOW MUCH for bottled water that is otherwise free from a tap? Look at the bottled water industry. Vitamin Water? $1.50 for a bottled water with trace amounts of vitamins.... people buying it up like crazy.
So PinkBerry is doing something right. There are threads elsewhere in the thread talking about many other competitors, including a big one based oin Korea.
Go buy 1 pinkberry for yourself OP. =)