Well it's not necessarily always cheaper. Most of the time, it's more expensive if you try to get the exact same parts in an oem machine. But if you don't need stuff, and know exactly what you don't need, then your price will go down. But if you're trying to save money by buying mismatched/generic parts, well you'll most likely spend more money. I feel oems offer a good deal to ppl who know nothing about computers and have no time to build their own.