One, you're probably having a tough time getting financed b/c used cars are always harder to finance than new cars. Two, it's not that great of a deal, in my opinion. Sure blue book my say that it's on par, but I personally feel that a used car that's that close to the 100K mile marker for a brand that isn't known for reliability and durability is not something that I'd buy. Three, it might be that you're disposable income is not high enough. For example, if you make $1,000 per month, but spend $900 of it on fixed living expenses and credit cards, you don't have enough disposable income.
When I bought my first car w/ Toyota, I was also a first-time buyer. My score was 680. I bought a 2000 Toyota Camry w/ 34K miles in 2004 through their college grad program w/ no money down. Although I was still in school, I was able to qualify b/c I was w/in 6 months of graduating. Plus, I had decent enough income as a bank teller to cover it.