If they haven't re financed and paid a prox 150 for it in 2013. Their payment is about 700. Which is what investors who want the security of being paid off would do. If they dump all the profits on the mortgage it should be paid off in the next year or two.
More likely the refinanced somewhere in the past two years and got their original cash down (30k) back out to invest elsewhere.
The purchase price is usually available if you look around and are curious. If you find a purchase price that is after the build that's likely the appraised refinance value. This has no bearing on what it's worth really.

