I think it would depend on the cost of the brake pads they offer at the shop in question, and whether the guy was also talking about resurfacing the rotors if needed. If it's just the pads that need replacing, you could replace those yourself if you have a couple of hours to spare.

As far as the axle seal goes, I'd try cleaning off the fluid that you see now, check the rear diff level (add some if necessary), then drive a bit more and see if it reappears. Sorry, but I've seen too many of those investigative news shows reporting on shady shops where some of the guys carry around a small bottle of all-purpose fluid just for the purpose of creating "leaks" that need fixing. Call me a cynic.

A second opinion is usually a good idea.