Depends on whether it's cracked, corroded, or just the gasket is leaking. The thermostat housing needs to be replaced or resealed.
We don't get involved with costs here because there's too many variables, but in this case I would guess a used part, if you pick it up yourself from a salvage yard, might run ten or fifteen bucks, and it should take about a half hour to replace it and address whatever caused the failure.
Be aware that mechanics and shop owners don't like customers providing their own parts. When the shop orders the part, they add on a small markup, just like any other store, but that profit goes to cover their costs if that part proves to be defective. If you provide the part and there's something wrong with it, or it's the wrong part, the job of getting it replaced falls on you. This is similar to bringing your own food to a restaurant and asking them to cook it for you. No one complains when food costs more in a restaurant than in a grocery store, but it's different with car parts.
If you want a new part from the dealer, someone at your repair shop will order it and have it delivered. The part won't cost you any more than if you bought it yourself, but in this case if the mechanic accidentally cracks it, it is up to the shop to pay for the replacement.
Tuesday, March 10th, 2015 AT 7:47 PM