Online rentals are posted by people who have very luxurious digs and want to harvest maximum hard currency in rentals. There may be plenty of places on the ground there that local people can afford, for a tiny fraction of what will be offered online.
That does not mean they would be easy to find. The best places to look are in areas where there is high tourist traffic during certain seasons of the year. There will be a lot of landlords renting to tourists, and you can still get a very good rate if you sign a year round lease, since a lot of them sit empty during the offseason. Most third world countries have very tight housing markets, and places fill up quickly when they become available. Usually you can find out about them only by word of mouth.
In the third world, a rental us usually nothing but bare walls, with no closet space. Renters are expected to bring all their furniture, sometimes even including a toilet. And there is no such thing as second hand, you will need to buy everything new, full retail, from merchants who will be delighted to overprice everything for foreigners.
Here is a useful site that will give you actual rents recently paid for every country.
http://www.numbeo.com/cost-of-living/