I've never had a problem affording Moe's Frontline, but I do just have the one cat to treat. I've heard of animals having allergic reactions or worse to some of those cheaper non-vet brand flea treatments, I guess they can be more toxic to the pet. That's what I'd be afraid of. The closest place to buy the Bio Spot is still half an hour away from me, but I go right past Moe's vet on my way to the office.
I've used bio spot for years on 3 dogs and never had a single flea problem...before that I used the cheap hartz drops and had good success as well.. My vet does not push his brands...if I have no problems with over the counter meds he says stick with it if it works..he is not out to make a killing..