When we started as full timers there were only a handful of companies that had true "full timers" RV insurance policies. Progressive was one of the cheapest and had the best coverage. The last yearly premium we paid was just over $1,000.
I don't know if it makes a difference or not, we always deal with Progressive on-line and never go through an agent.
We just called them for an estimate for switching from our full time policy to a regular RV policy and they quoted us a little under $800 per year.
Maybe your RV is valued a lot more than mine?