advice needed

[Derek Young]

Help needed please....

I am n negotiations on a building with one small commercial space (approximately 800 Sq ft which rents for $350) and 4 one bedroom apartments (rental incomes of $330, $360, $410, $450). The building is $75000, insurance runs $1200 and taxes run the same amount. 

I have a down payment of $30k but can't find a lender who will cover the other $45k. The seller Is willing to entertain offers of selling on contract with a balloon payment but I am lousy at figuring out terms to present. Can someone help me come up with a mutually beneficial solution for the sellers as well as my situation? 

Backstory: the sellers are retiring from Indiana and moving to Florida.  They are selling their properties here for cash to be used n the new market. My wife and I have decent credit scores, low to mid 70s and the $30k is the extent of the cash that I can get my hands on.