Vets can be expensive but it is worth it for the well being of your snake.
A routine check up at my vet costs me $35 USD.
My rescued Boa had a respitory infection which set me back about $150 USD.
The benefit? I helped nurse a sick snake back to health and I have had no problems with her since then. It is cheaper in the long run as the vet can offer expert advice and save you money in the long run.