What is the best funding source/investor for conforming loan purchases where the buyer is using business funds for down payment (20%) and closing costs?  The other issue is the buyer's CPA willl not provide a letter for the stability of the business in the file, nor will he provide a profit/loss? 

From a conforming standpoint...this deal is DOA.

Not dead - just need to season those business funds in a personal account.  Chances are you will get only a 1 month bank statement requirement through DU so 30 day seasoning (maybe a tad longer depending on when statements are sent) should be okay

Even with seasoned funds the profit and loss issue will still be a problem. Most lenders require them for any application outside of the 1st 120 days of the year. So if the guy filed 2011 early and then applied in February or March...this may work (again...assuming the business funds are seasoned).