518 46re smoked

There are many definitions of "rebuild". Some cheap jobs are a gasket and seal kit, used converter and a can of spray paint(AKA) "Patch Job". Other rebuilds include bushings, washers, electrical components, rebuilt converter etc. If you're going to go the transmission shop route, look for a long established shop with long ownership and a BBB rating. Some shops are here for a long time, others only a short time while they take advantage of those not too well informed. Many cheap jobs done cash only, and if you have a warranty issue they don't even know you. Saw this type come and go many, many times in the years I worked in the industry. I used to call them the Cash and Go Transmission shops.
For parts alone, for a complete rebuild, the bill, depending on the transmission model, could run anywhere from a couple of hundred dollars to damn near $2K. Add the labor and warranty and go from there. The members that have worked in the industry know what I'm saying.