I think for beginners (i.e. buying their first guitar), it is better to buy firsthand from a shop. Because they're still new, so if it turns out someone in the buy/sell is cheating, they won't know early enough and by the time they realize it, it is too late to reverse the deal...
I recommend the Timbre and Smash electric guitars at Standard Value. If you like to play heavy stuff, the Smash S2 would be more appropriate. Great service, and Mike's quality of setup means you probably won't have to service it for quite a long while.