I use these guys more often: mazdapontiacgmcparts.net
Prices are a little more but they have better customer service (email and phone to a live person).
Sometimes they send out emails offering free shipping on orders >$50. This usually ends up cheaper than GMPD.
Another thing I’ve noticed with GMPD is that most parts I lookup are “special order” parts and their policy says special order parts are non-returnable. Showcase Pontiac Mazda GMC just has 10% re-stocking fee.