@Simplepuravida
Crazy suggestion... There are semi-prefab concrete block houses that are very reasonably priced; and the manufacturer can most likely recommend a 'local' that is experienced in erecting them. You can have them draw up a plan as per your needs/wants; and you could also add vertical re-bar up through some of the blocks in order to create a more seismic resistant structure. Usually the price from the manufacturer is for walls only; you would have to work with the builder/installer to come up with a price for his labor; and then ask him if he would have a few hours to spend, with you (pay him for his time) to determine the approx. Costs of materials for excavating, Septic and well if needed, footings, windows, roof framing and roofing sheets, and of course, all plumbing and electrical rough-in materials; rain gutters, interior/exterior tile installation, exterior paving for walkways; patios, etc; rain gutters. and installation of all Fixtures (plumbing and lighting).
The pre-fablock house 'walls' can go 'up' in less than 2 weeks.... and from there, it's up to the size and layout that you have decided on as to how long it can take to be live in ready.
In case you haven't lived here before... I would come and rent for a year -ish; that way you'll realize just how much house you will actually USE and how much time, for example, you'll spend in/on your outdoor spaces. I found that I am out more than I am in. That's why I came here.
In theory, I'd be OK with a kitchen, bath, and one indoor sleeping/eating space INSIDE... but would build the OUTDOOR spaces (semi-private in front; more private in back) twice as big and with more amenities; like easy access to a sink; extra electrical receptacles; or even all-season blinds to make a patio a private sleeping space at night; etc. I really don't like all these walls.
It's easy to look at the pre-fablock houses on-line; .they have tons of options to choose from and like I said, you can customize... 'outsiders' like north Americans and Europeans need closets, and bathrooms bigger than airplane bathrooms... Ticos live without them. Don't ask.
Almost forgot.. The reason I suggest this is price; the pre-fab concrete houses (don't even look at the ones that use panels) are very reasonably priced. 90% of all new homes where I am in western San Carlos canton are pre-fab. Once finished; you wouldn't even know. Block is block.
Good luck to you!!