A modular home is what you will want if you're not going to have one stick built. A manufactured home or mobile home is not. Banks typically won't lend much for either manufactured or mobile. Values on these go down, never up. If you're going to do it, at least go with a modular home.
There is minimal cost savings if any with a modular versus stick built... infact when we looked, modular was more expensive than stick built.
