1 looks to be a lot rental of $866/mo OUCH.
2 may be on its own lot outside of a park or HOA.
3 looks like lot rental $855/mo.
4 is another lot rental in a seniors park.
Those are all in California on small lots. Keep those prices in mind and check out prices on one in Alabama:
ValleyMLS.com
$100K, and it includes the home and 13 acres. Taxes would be around $250/yr.