First of all let me state that this year didn't go exactly as planned. What we intended to be an extended visit to our home state of 6 weeks ended up being 6 months mainly due to unforeseen doctor visits. That being said, the year was split half and half driveway surfing and camping on government lands.
For staying on government lands and us being over the age of 62 we have the Senior Pass America the Beautiful. This pass gives a 50% price break while staying in the multitude of government controlled lands. Check it out online, well worth the $80 price. I can't answer your question specifically because I didn't keep records but the most I spent per night was $12 and the least I spent was $2.50. Free is an option on BLM land but you don't need a pass for that. All of these places offered no hookups. Dry camps all with potable water at some local point. For water I carry an additional 50gal in my truck bed and go into camp with my fresh tank full.
This year I don't plan on getting blind sided and stuck in the home state. I hope I've learned from past mistakes. Learn something new all the time.