Regardless of the CAP rate, without a down-payment, banks, in their "infinite" wisdom will not touch a loan. Seller second does not mean anything, either.
Your only options are to "be the bank" or find someone who is interested in being the bank.
If you choose to service the loan yourself, a company like Virgin Money http://www.virginmoneyus.com/RealEstateLoans/tabid/55/Default.aspx can handle the paperwork for you.
If the property is indeed at 17 CAP, and your buyer has decent credit, then you may want to contact one of the private note purchasers, such as, http://www.thenotebuyer.com/ , http://www.bostonnote.com/, etc. They will help you structure the loan and cash you out at the closing.
Another option would be to contact your area real estate investment clubs http://www.nationalreia.com/clubportal/795files/directory.cfm?clubID=795&pubmenuoptID=11912 to see if any of the members would be able to structure the deal while benefit decently from the transaction.
Best of Success!
Mar 1, 2009