Early payback with creative financing!?

[John Magana]

I am about 6 months away from starting my investment journey meaning starting the process of buying my first property. 

My question is this. The seller is asking $340,000 for a property. I offer them 250K at 3% seller financing over 30 years with 25,000 down. This means at the end of 30 years they will have made their total $340,000 asking price. However I am able to pay off the property in 10 years meaning the seller only ends up making $35,000 in interest making it to $260,000 versus $116,500 in interest to get to the $340,000.  Is this a thing? and if so is this simply part of the underwriting of the loan? Has anyone seen this before? Thanks!