My suggestion is go to your bank/credit union, ect, whoever you deal with for you day-to-day banking. Sit down with someone and appy, you can probaly even go online and apply. For a private sale like this, that would be your best option. Other option is to look at finance companys if the banks can't help you out. They cost more to borrow from but depending how your cash flow is, you can pay it off sooner than later and save some $ and get your ride. Depending on your situation there is several choices for you to get financing. My .02 cents.
I'm not an expert on the US banking system but have finance expeirence north of the border

If you got questions, msg me, glad to try to help.
**edit** What I would do and did, get a personal line of credit (loc). Like a credit card but with personal loan interest rates, usally credit history will dictate the rate. Plus it lets you pay the way you like, most times min pymts at $120-180/mon. If cash flow is good for you, pay more and save yourself $$. Most financial institutions offer an loc.
_________________
2005 KJ Sport 3.7L, select-trac, trac-lok, K&N air, Mopar skids, 245/70R16 GY Wrangler Silent Armours, Draw-Tite Class III Max-Frame Hitch Receiver, PIAA Xtreme White Plus bulbs. Built: 08/04.
Exhaust, lift, rims painted black, Duralined, roof basket, and Renny light bar to come!
http://www.cardomain.com/ride/2305866
L.O.S.T. Member# 173501