Buy in cash and then mortgage?

[Yoni R.]

Hi I am an investor from Miami. I wanted to know if buying houses in cash and then getting a mortgage on them is a good idea. For example if I buy a house for 100k in cash and the market price is 120k will I get a mortgage on the 120k or on the purchase price of the 100k? Will the interest rates be the same whether I get the mortgage before or after?

Thanks!