I have the pass. $225 for non-resident, cash or checks only. It is good for only State Parks, no feds. It covers camping fees on a site with no electricity. It also covers day use fees. You can stay 14 days out of 20 in one park but then must move to another. After you've been gone six nights, you can return if you wish. Usually a water source, maybe just one main one. You can use all facilities, showers if they're available. I'm told the showers at City of Rocks SP are coin operated. Whatever that campground has, you can use it (except extra stuff, like tours where everybody pays extra). If you want electricity and it's available, it's $4 more per night.
This week, I have been to Conchas Lake SP and there was one other camper.
I am currently at Santa Rosa Lake SP. The non-electric site loop is a mile or two from the electric one, which is where the showers are located. There are two other campers in this non-electric section. Almost deserted. In the hookup section, it's pretty crowded. I had to drive over there for my shower today. I'll sacrifice convenience for privacy.
If the campground is one that's self-registration, you do not have to complete the envelope thing. Just drive in and park. Now that I think about it, even if you don't camp there, you could just stop in, shower, fill your water containers, dump your trash and tanks. Hmmm...not a bad deal.
Check the website or call for seasonal closures, especially in higher elevations this time of year.
Happy Trails!
Edited to add: I bought this pass a few days ago. It was $225. Don't know where $250 came from?