We paid $40/night - missed the AAA or Good Sam discount.
Entering the fairgrounds is somewhat confusing. There are about a dozen nice spots on a grassy field with a gravel site with FHU. The camp host will probably take you through the field to pull-thru otherwise all the sites are back-in. The other 60 or so sites are in a gravel & dirt parking lot. The helpful camp host said it doesn't really ever fill up. However, no camping during its fair time over Labor Day weekend.
Sonora is large enough with a wide selection of stores and activities.
I would stay here again when passing through.