I wouldn't ask about 'cheap' wedding photography on Talkphotography. MrSmith's rather predictable response is probably the nicest you'll get!
FWIW, we were very lucky, had a friend's fiancee (who's in his final year of a photography degree) do it for us. We donated him my wife's car (we were emmigrating, and it was only worth £200), hired him some prime lenses (cost £250 for about £12k's worth of glass for the weekend), and lent him my 5DII as well so he had 2 pro bodies. I've yet to see anyone who's seen the photos who has taken or seen better themselves. Sometimes, gambles can pay off.
The alternative would be my friend's wedding in the Lakes. She paid c£5k for a 'pro'. I had to rescue her with my snaps from the back, taken on a camera I'd had for less than a week. Sometimes, gambles don't pay off.
Amateur togs can be crap, pro togs can be crap. I'd guess there's possibly less chance of the latter, but there you go…