Offer in on 8 plex - 35K noi, with creative financing

My wife and I were exhausted after rehabbing our 4 unit building in Crystal.  We got new tenants and higher rents, but we were burnt out.  One of my realtors reaches out to me last month about an 8 plex in Southern MN I have long had my eye on.  First reaction was 'pass'...we were too tired.  But good deals just start to bug you.  I had been reviewing deals in the Twin Cities, and seeing some awful numbers.  This deal kept coming to mind...it is a potential 12 cap.  We looked at it two weekends ago, and saw that it was well maintained.  The seller had it listed in 2012 and got no offers. 

Having just rehabbed our 4 unit to the tune of 35K, we are in dept payment mode.  But I started doing homework on this place anyway.  I used the BP Rental Property Calculator and figured out a max offer.  Then I contacted two banks.  I also contacted some contractors when I saw the lot fairly beat up, and got a bid from one.  

Seller is asking $300K.  We bid last Friday $255K, but with, I kid you not, 10 contingencies.  Among them, some of my favorites

a)  A $25,000.00 escrow for lot repair, remains payable to seller after one year.  I have an actual bid on this amount.  I'm sure it can be done cheaper, but the bid says what it says.

b) Seller carry back 10%, amortized 30 years, payable in 5, but interest free if paid within 6 months of closing

c) Seller gives me full rents in month we close

d) Seller pays $3K of closing costs

About the building.  8 units, average 2 bedroom rent (6 units) $580.00, 1 bedroom unit (2 units) of $450.00.  Laundry income added $100.00 a month.  NOI is 35K...after financing and we put 10% down, will cash flow about $1500.00 a month.  

Max offer will be $275K, but will want more cash coming back in that instance.