First thing I would tend to ask is this: Did they put your pug under anesthetic at the shelter for neutering or did he arrive already neutered? Pugs can be very tricky under anesthetic and a vet that does not know the breed well may not be a good choice. If they didn't alter him, meaning he arrived neutered, then a blood profile would be a smart idea as it will warn against any difficulties. He'll be under for a fair bit of time to do the extractions and cleaning so it's important to be sure he can handle that first.
Sometimes the least expensive route is not the best route when dealing with a pug. JMHO.
"For every animal that dies in a shelter, there is someone somewhere responsible for its death".