So I've been researching pretty much all day on my options of neutering Mason and I came across a website of an organization called Friends of Animals. You can buy certificates for spaying/neutering (prices vary by gender and type of pet) and they have a list of all participating veterinarians in your area. And guess what, I found my vet on the list

!!
So I called my vet, asked them if they currently participate in the "spaying/neutering program" of Friends of Animals, and they said yes. So all I have to pay is $54 for the surgery (well, and $65 for pre-anesthetic bloodwork which I will definitely do for Mason).
It's a little disturbning to know that this morning, I was about to pay $340 and now I am paying $119 for the same surgery, by the same vet, at the same clinic!!