, sealing up lots of air leaks with expanding foam, replacing the front and rear doors, paint the porch, install an handrail, and a few other things I am forgetting I am sure.

We lived in it for 4.5 years and did little things gradually to bring it to life: new carpet in a bedroom, new bamboo floor in another bedroom, patio area with a pergola, seal coated the driveway, etc.

At an 8 cap resale is 600,000Take 600,000 minus 6% commission = 36,000 Also factor 20k in closing costs and legal for resale600k - 56,000 = 544,000If the units are totally stripped rehab varies by area with parts and labor but figure if windows, roof, mechanicals, parking lot repainted and sealed about 13,000 a door depending on size of the units and mix.20 units by 13,000 a door = 260,000 in rehab600k - 260,000 - 15,000 when you purchased for inspections and closing fees - 56,000 listed above for when you resale as a seller is 269,000.So the most you could pay is 269,000 for this vacant building and have zero equity after rehab and just have the cash flow working for you.

You need a Purchase & Sale Agreement to seal the deal.

I think the two panes come in a pre-sealed 'kit'.  

seller disclosure looks good...grease fire in 2008 which required taking both sides to studs, sealing lumber and all new plumbing/electrical/sheet rock, trim, paint cabinets on both sides.

If my offer price took into account initially receiving no commission, then I'd have likely initially offered it including my commission, but agree to forego it if that sealed the deal.  

If you are sealing the deal on your end properly, you are golden.

Its in need of finishing drywall, sealing the windows that look like they were put in improperly, new flooring in the living room, and bedrooms, paint, and all finish work and some work needed in the kitchen.

A non-sealed (radon compliant) system is 1/2 the cost.