In the event we do locate one, you should be aware that most require a large down payment (usually 20% to 25%), the interest rate will be considerably higher (probably 6% or greater ... current bank rates are in the 3.5% range), and you will need to obtain financing to pay off the owner in three to five years (the "balloon"). With homes selling quickly, there doesn't seem to be a reason why an owner would elect to act as the bank ... unless there's something critically wrong with the property (bad foundation, structural damage, etc.).
I hope this explains matters a bit for you. If I can be of further assistance, please feel free to contact me.