Owner Carry on a vacant lot

[Susan St. Martin]

Hi Everyone,

This may seem like a simple thing but it's been awhile since I have done this. We are buying a duplex and we are financing that outright and then next door she has a vacant lot that we are going to purchase too. She has already said she would carry paper. 

So the purchase price would be $60k - the plan is to put another duplex on in it in the near future - so a balloon pymt would be fine.

Can someone give me suggestions on how to write this up? I was thinking a 5 year balloon maybe 6% interest. But wasn't sure on the amortization. Do you only do 20 years on an amount so small?

What is the calculation for figuring out the payments? Also would like to know how to figure out interest only payments? 

Thanks in advance.