I lived in a used, very used, 1975 mobile home for some years. There are some drawbacks. Many of the older homes are not solidly built and are poorly insulated. And here in TX you cannot get insurance on them.
They can be bought very cheaply and if you are able to do the upkeep yourself, and live without insurance, they can save you a great deal of money. But you could have high heating and cooling costs.
After Ike clobbered the old house I bought a new mobile home. It's 940 sq ft, energy efficient, and was within my budget. My heating and cooling costs are almost half of what I paid in the old home.