No, Apple is usually expensive. And installing on the Pro looks pretty damn easy. The best place to buy is the cheapest place that isn't a rip-off joint. There aren't any knockoffs of 750GB drives, so that isn't a worry. Newegg often is very low. CompUSA occasionally has deals.
Although it may actually be cheaper to get multiple smaller drives. Unless you are sticking 4 750GB drives in there. Check the cost per GB.