I managed to buckle three alloys when I drove to Romania. At the next MoT the tester told me I'd have to get them straightened first or he'd not do the test...
I took the Multi to an engineering shop which specialises in wheels, they only charged £50 to take all four wheels off the car, remove the tyres, straighten and refit. Seemed a good deal to me!
They said they'd straighten, remove kerbing marks and powder coat for £50 - £75 per wheel depending on the work required.
Dunno if these prices are typical throughout the UK though.