Where can I find $250,000 for a down payment?

[Stephen Hollenberg]

I'm under contract to buy a 6 unit, mixed-use property with seller financing. The seller will provide $700,000 of the $945,000 required. They are giving me 45 days to show proof of funds for the $245,000 so I need to find it!

-I can't take any more loans from my 401k.

-I have 3 properties right now:
    -Property A, worth $400,000, is currently financed at around 72% with potential to pull out $31,000 to get to 80%.
    -Property B, worth $500,000, is currently in the process of being refinanced at 80% to pull money out to buy a separate property.
-Property C, worth $600,000, is my primary residence currently financed at 86% with potential for a HELOC to pull out $23,000.

If I can find $245,000 at 6% the property will still cash flow $400 per month at closing after all expenses, 5% vacancy, and 5% toward repairs. With potential rent increases and filling a currently vacant unit, it will cash flow over $2000 even fully financed. 

Any help in where I should look would be appreciated!