There aren't many people around who I'll recommend to work on the older Colt action.
NONE is better then Colt themselves.
They know what they're doing, have all the needed parts, and will do it RIGHT.
Cost is very competitive, and turnaround is MUCH faster then any other.
They'll give you an estimate before doing anything.
Value of an original 357 depends entirely on actual condition, and whether it has the original grips.
Like all Colt revolvers, 357 prices are going up fast.
Colt only made around 15,000 357 models between 1953 and 1961.