I don't know the cost but we had similar problem at our church building,roof(like a carport)was sagging. The brick column was loose. My dad fixed the whole thing by putting a round steel "pole" with steel plate added at top & bottom after jacking the sagging part up & then redoing the loose bricks. Hoping yours is not sagging & just needs new support(could be the metal studs-wouldn't rot out.If it is sagging it would have to be jacked up in that area of garage to get the studs in place, so they would have to get that cement in 1st, then jack ceiling up & then put the studs in & secure & then brick around the studs. My son used metal studs in his basement & liked them. Studs could be bolted into new square of cement if it is crumbling also, probably would need to replace 1 sq ft or so. Need to check requirements for your area. Did I make sense? cement has to be stable & probably new,then studs in place & brickwork.Jacking up ceiling would greatly increase costs. In TX. I think metal studs would work better-no termites. Imagine someone else can give you more info.