I do it for £15 ! It's not a lot of effort really, and i earn a whole load more than i could doing a real job at 15. It takes like 15 minutes to order, and then 20 minutes to build. Start up the OS and press ok every few seconds and your done. Easiest £15 i could possibley make at 15.
I do about 2 to 5 a week (including upgrades), big school.. word gets around
Then if it breaks within 90 days i will personally pay whatever it costs to fix it. So far i've never had to do this.