First things first. Does where you are wanting to put it have zoning regulations? While I do not think that area have strict ones always a good first step. Pay for extra insulation not the regular stuff.

Mobile homes depreciate. They hold no value at all compared to even a poorly built conventional home.

Do you live in a mobile home? Or a conventionally built real property?

I'm not quite sure I understand your question. I live in a manufactured home. It meets all the building codes and standards for my province. However, it was constructed in a factory and trucked to the site in two pieces. It sits on a steel frame (that it was build on in the factory) which itself sits on block pillars (it has a 3' crawl space). It is not a modular home (as per my understanding) which is also constructed in a factory but is later installed on a foundation (often with a finished basement) and is not subsequently movable. I hope this helps.

Bruce did a good job of explaining: manufactured homes (used to be called mobile homes and before that trailer houses!). Modular homes is sort of like stick build homes but has a lot more limitations.

Is something like this a possibility for your situation?: Honomobo homes

When delivered, they have the advantage of being turnkey as soon as you hook up to utilities, many of the models are very compact, they can be shipped to you, and they meet building codes.

Wow kudzu9, those homes are amazing! I would have never guessed that they were modular without seeing the link.

they might call their homes 'modular' but that is NOT what most folks think of as modular, but rather as 'shipping containers' IMO.

Yes, they are shipping containers, which makes them structurally stronger than the type of modular framing I think you are alluding to. And you would have a hard time realizing that that was what provided the structure after they were finished.