Damn, that sucks. Wonder if he followed the TSB set out by Ford. It mentions how to remove them to minimize breakage, as well as where to put the anti-seize when putting them back in (it's not on the threads) to minimize future breakage.
I guess he must have dealt with this issue before if he had the tool to remove the broken plugs.
Either way, if you're going to pay someone to do it, it's best to "shop" around, as different places have different prices. Some places charge a set rate, while others charge a cheaper flat rate and charge for every broken plug. It probably wouldn't be a bad idea to ask about their success rates.
It's also better to shop around for the plugs. I think they're around 9 bucks a plug on rockauto.com.
I posted the TSB in a thread by alakanexpy. I would do the when he does his Expy, just so he can have all the tools there. Since there's less chance of breakage, maybe even practice w/ the F150 before doing the Expy.