I have a £40K, 100 Hp microlight with all of the risks, hull, 3rd party, passenger etc and I have 400 hours microlight and 86 hours other. The cover is just for me and LAA agreed test pilots It just cost me £1140 to renew for Europe wide cover. Oh, it usually lives in an open fronted hangar.
If the power counts for anything in insurance, then your estimate seems reasonable. Are you the sole user?
Rans6....