It depends on the part. When I had my Grand Prix and I needed wheel bearings I could have gotten all 4 for under $100, but I opted to spend around $100 each on some Moog's for the 3 I replaced. The 3 year warranty and peace of mind that the build quality brought was worth it.
In the end you have to weigh your options, look at warranties, reviews, and figure out what is going to work best for you.