Depends on motor I would imagine. Some take longer than others but I wiuld figure anywhere between $200 to $400 labor & you provide the reeds. If mechanic has to supply them he deserves SOME markup on price of reeds I'm sure. Just a guesstimate.
'98 Tr20 Triton completly updated & rigged, 05 Magnum c-channeltrailer
'94 Merc 200Xri completly rebuilt & noseconed/low water pickup lower unit.