Just pick up the phone and start calling - you might find one who has some experience. I never trust a vet who claims to know it all.
Female gliders will NOT self mutilate when they go in to heat. Even a neutered male will "do the deed," so get ready for that. Think of it this way - a human male who has had a vasectomy can still perform - they just can't father children. Same with any other species - including gliders.
Perhaps you would like to get that vet in touch with the SUGAR group for the most up-to-date information and statistics on sugar gliders. If so, please let me know.
I drive 6 hours one way for quality vet care. I do this because I decided in my mind that nothing - NOTHING - would keep me from providing the very best for my babies. You must decide what you are willing to do and do it. For the price you are looking at, I bet you could find a vet within a 3-4 hour drive that would be significantly cheaper. In the end, you would save- even with the cost of driving. Something to think about.