Find a good shop and don't leave your car there.
I would recommend the opposite on that latter part.
If you're waiting on it, they're going to be more likely to give it to whoever's available, i.e. low men on the totem pole. Give them some breathing room and there's going to be a better chance that your car will be kept out of inexperienced hands.
I hate to recommend the dealer, but in this case it might be worth the cost. Whoever sold you the car is probably going to be less likely to damage your wheels and deny it.
Those tires shouldn't be that hard to change, though (relatively large sidewall for the wheel size). And most shops have retired their old (good) tire machines with the steel foot (part that rides near the wheel and guides the tire)- those have to be setup right to avoid damage. Instead, most have a machine with a plastic foot that is intended to touch the wheel. More idiot-proof.
edit: do you know for sure that those wheels are cast, btw? I would think they're forged for that damned price. Not that it still isn't an absurd price for a one-piece forged wheel. editagain: missed above link, nevermind.