it must depend on county because mine are more like $45/year and I only told them the trailer was worth $400. I believe it's more the first time though, add in the cost of the plates and whatnot. I'm in Douglas co btw. Trailers went up a bunch a couple years ago when the did the fee restructure. And you can't go without registering or they nail you for not having it registered now even if you don't drive it for a couple years.
I don't mind paying for my cars, camper, etc., and keeping up our roads, whatever, but the trailer fees have gotten a bit excessive imho.