All the answers above address plenty of important points. However, one critical issue is whether you qualify for a mortgage to buy that house, given that your “income is low compared to a mortgage cost”.
Banks use several simple qualifying formulas, one of which is DtI (debt to income ratio). It means that they want your total monthly expenses toward house ownership (mortgage + insurance + taxes + common charges) to be less than 40% of your monthly income. Check your calculations now if you still qualify for a 20% down mortgage.
If not, perhaps you qualify for a smaller mortgage, instead of a more traditional 20% down.
Whatever mortgage you qualify for, it is not just typical to purchase property using mortgage. It also makes sense financially, at least in most cases. You get a chance to borrow money at one of the lowest rates of your entire life (compare mortgage rates of 4% to a typical credit card rate of about 13%), and, normally, attain the highest leverage / borrowing capacity. When you pledge your house as a collateral you can normally lever 5 to 1, while when you pledge your portfolio of stocks for example you can normally lever up up to only 3 to 1.
