I think the question should be rephrased to: How many people keep their reptiles on pine bedding? How much success have they had?
If people could keep their snakes on cheap pine bedding: Why don't they? Reduced lifespan? More likely: Seriously reduced lifespan...enough to discourage anyone from recommending it... Cost of substrate is trivial compared to a vet bill.
If you do decide to keep your snake on pine bedding: Do let us know how it turns out.