I would find a comp shop that's NOT a big chain
Psht man, the little guys (atleast around here) will rip you off just as bad as any big chain store. People around here are scandelous and just hunt down people who don't know anything about computers. Hell man when I walk in there, he talks to me like I'm an idiot and I don't know sh!t. Guy tried telling me that a 'TRUE 350W has more power than this 420w over here cause it's not TRUE POWER' ......dude was an idiot, all his PSU's had a +12v rail of 15 and he was trying to tell me you could put all kinds of stuff and the PSU would handle it. This is coming from the same people who put a glob of thermal grease on my CPU core and failed to realize that the stock heatsink had a thermal pad on it....so needless to say that caused instability with crap all over the connectors and a cleanup and format later insued.
I would suggest you do all your own research and yeah you will indeed learn a lot from these forums. I know way more now than I did in july and trust me once you start getting into it you'll just know so much crap it's dizzying.