The other thing to consider with looking for a rent to own is that the seller has to be able to afford to move on without the lump sum from the house. If they can't purchase a new house without selling the current house they aren't able to consider a rent to own situation. You asked about new construction...the builder more than likely has a loan on that house that needs to be paid when the house sells. They are not usually willing to wait 3 or 5 years to pay the debt off. They also would have to take into consideration many things like...what if the renter loses their job and can't buy the house, what if they trash the house and walk away, what if they don't keep insurance on the home and it is destoyed by fire?
There are sellers that are able to consider a rent to own but they can be challenging to find and generally a decent down payment is needed. Good luck to you!