A proper cage for a large boid can be quite expensive and while it sounds repetitive, yes, the food gets expensive. My cornsnake eats a mouse a week, so even I'm buying them, it's a max of 4 bucks a month. My burmese, however, gets one rabbit or piglet a month, which can range in price of 8 to 20 dollars.

I would imagine that herp vets charge more to work with large boids than with little punk cornsnakes as well - and I don't blame them, hehe.