ive always built my own. Most worked first time, or had some small, easy fixed problem (such as a bad psu, or crashed hdd)
ive built quite a few. Right now, I have 8-10 which are working, and maybe 2 which have a few faults.
I've built my own since 2003. LOL but I think I build one every 6 months. I get bored of the old ones.
I also build for others and charge between $100-200 for labor. Put it this way, all my builds are paid by customer builds or repairs. I've made more money off of the repairs.
I'm no tech and still learning but it's fun to charge $50 to install avg free edition and wipe some viruses away.