Regarding a local shop, depends on the shop. As mentioned the MM battery swap is pretty simple, just have to worry about some amateur slipping a screwdriver and scratching the back (or stripping the screwhead).
If it's some watch kiosk manned by an hourly peon at the mall, I'd pass. An experienced watch and jewelry repair shop, I'd be fine.
But if sending it into Oakley is fine with you, go for it.