Buying land off a neighbor so I can subdivide the property

[Jason Yarusi]

Hello

Quick scenario is I got an off market property large enough to subdivide square footage wise however the lot is odd shaped so when I split the lots to meet the minimum widths the one lot falls short approximately 800 square feet. So I went over to the neighbors and asked if I could buy a 7.3'x100' area I need, which ideally sits right behind a fence they built separating their beautiful property from this dilapidated one.

Good news is they are open to it. We talked a bit and they have no idea where they sit on pricing. Being NJ there isn't a ton of land to these parcels. I believe theres is .18 acres and mine is .41 acres. so I would be asking to buy around .02 acres if I did my math right. 

So my question is has anyone been in such a situation that has ideas about a win win for myself and the homeowner purchase right. The first number that came up in my head was $15k and a new fence.

If I can't subdivide I will keep house and add 1800 sq ft addition and house should be in $680k to 700k max. If I can subdivide I will be able to put up two houses that I will plan to list in high $500k to low $600s each (smaller lots and smaller homes but new).

Thank you.