I purchased complete bikes, until one day, I realized I was beginning to replace half the components. If you are happy w/ a complete bike's component spec. you can save $$. Now if you look and a complete bike and say I want different tires, cockpit, drivetrain etc. it time to go custom build. A number of years ago my buddy decided he wanted to do his first build. He made the majority of the component purchases online & Ebay. He ended up @ the LBS a few times (small parts) and my house for brake bleeding, headset installation, steer tube cut. He definitely hit a number of bumps in the build but overall he felt accomplished but he did end up spending more than he thought he would.