at my lbs, it's $5 for a new tube and $6 for labour.
two years ago, one of the shop regulars comes into the shop, riding his then-brand-new trek 5900 [he has since moved on to a specialized s-works e-5 and a giant tcr 100]. he points to his stem, which is twisted slightly off-line and asks us to fix it. one of the guys says "just take an allen key, loosen the bolts and straighten the stem, it's easy." the customer has a puzzled expression on his face, so one of the guys takes a park multi-tool of the wall to show him. the customer: "wow, you have those things here?"
okayyyyy....