In Illinois, I got a rude surprise on that. On used cars bought from a private seller, typically the fee we pay at registration is pretty reasonable. It's based on the model year only, not the purchase price. They used to base it on the price, but everyone lied of course, so they gave up. I assumed the same low fee would apply on my mini MH. My wife handled it at the DMV, and the tax was 5% of the purchase price, not the minimal amount. Somehow there was an exception, and DW got the impression it was for vehicles they knew would be not typical.