The cost can be as much or little as you want. Especially if
1. You already have truck.
2. Don't mind do it yourself maintenance
3. Buy used trailer at a reasonably good deal.
4. Have a free or inexpensive place to store it.
For others like myself, there are some areas where my spending is above average (automotive) and below average on other items.
I do think anyone who tent camps or enjoys the outdoors should give RVing a try if they can afford it. I have some good friends who tent camp a lot. They love scenic national forests and parks. They are probably going to leave a big fortune to their kids. An RV of some type would seem to be a no brainer. Especially a smaller one which fits in public campsites.