Here's a really good thread on boosting that fell off the first page:

http://www.dual-boxing.com/showthread.php?t=30644

Personally I wouldn't boost with a lock, mage, or ret paladin. It might be ok up through vanilla instances but once you start getting up to TBC dungeons it's going to suck pretty bad. The norm is a prot paladin or a bear/druid. to boost. But you work with what you got!

Repair bills I honestly can't say I've ever paid attention to them. Except if my entire 80 team is wiping that crap can get expensive quick!