The pricing is rough but any vet is going to prefer you be on prevention regardless of where you get it than not.
Simparica Trio is a good product. So is Bravecto, though doesn't cover heartworm.
Honestly, the dermatitis, skin infections, intestinal parasites, and heartworm that comes from not being on prevention is one of the most depressing and frustrating aspects of working in vet med. Too many dogs have died early and miserable. I hate how expensive it is too, but the long term costs both financially and to quality of life to NOT being on prevention are so much worse.
He also takes sentinel, which he now does as yearly injections, which helps cover the heartworm prevention. I may have found an alternative source for the Bravecto that is discounted about 40%, but I'll have to wait a few months now to try it out.
I'm mostly just annoyed that the distributors of Bravecto seem to be charging roughly the same amount per animal, regardless of weight. Excepting, of course, instances like mine, where I'm forced to buy a second tablet due to their limited range of available doses. Lucky me, paying double simply for having a large dog.