That's interesting as I have RLI and I have it for events only. I pay $249 a year with a million dollar coverage.
I used to have that same insurance from RLI and it was great for shows, in-transit etc. But they would not insure my studio or my retail (barn) on our property because of what I made, so I had to change companies (this was in 2002). I now have coverage that covers events, traveling, everything I need for shows and my other buildings. We had to divide our homeowners insurance policy and cover the studio and barn with a BOP (business owners policy) and the rest with our regular home owners insurance. The BOP alone runs about 550.00 a year.
Being a potter I had a hard time finding the right company. I believe I am a high risk because of my kiln in my studio and that might be the case with you also. Which is why they won't let you have event-only coverage.
If you got a quote from RLI on event/ studio insurance, it sounds like they carry what I need now. I will have to check it out and see if RLI compares to my current company.