This is a great website that I found to search for land. It seems this is a struggle for many people and it was for me.
www.landsofamerica.com
People seem to always be looking for inexpensive land and the below link is just something I stumbled upon with great views in SE Oklahoma. It is very rural and has no utilities or hope of having them unless you provided.
I have camped here several times, once on a tarp because I forgot the tent. And I am not necessarily a bigfoot believer but if he were living somewhere this would be a great part of the country for him to be.
It is in the 1,000,000 acre Ouachita Mountain Wildlife Reserve.
Hope this is in the right spot on the forum.
http://www.landsofamerica.com/america/index.cfm?Detail=&INV_ID=711433
Not bad. Seems like a good search engine for large parcels. It seems to bring together a lot of other search sites. (United Country, Century 21, etc.)
I found a lot of luck with Realtor.com
I would do an advanced search.
I would type in an area.
Add all surrounding areas for 20 miles.
Tell it to search for just land.
Then add a minimum number of acres I was looking for (5-10)
I would tell it to sort the results from lowest price to highest.
It gave me a good perspective of what land values were in certain areas, and a good starting point to look from or to move on to another area. I hope this helps if you are still having trouble.