Should we do the project?

We're a family of 4, curently we have let's say less than $250,000. We dream of building a small apartment (8 rooms) which aproximately cost almost $400,000. We've started the project a few months ago. We would need 2 years to complete the project and providing all rooms are rented out, we probably can get up to $80,000 / year thereafter. Our yearly income is aproximately $70,000. Recently, due to national economics depression prices have gone up and we have no idea when they'll stabilised. We can't get a loan anymore. So if prices is going up again we might have to sell our only house for less than $240,000 to cover up the project. Do you think we should continue our project and risk the house? We're quite sure that curently the demand for rooms is moderate. Thank you.