You may be able to find a used Colt New Agent for $700 ish. Probably a little better than the RIA in quality.
Also, I know you said single stack for the thinness, but you may want to consider the Ruger SR9c. Watch Hickok45's review of it. It's thinner than a Glock and AFAIK its the thinnest double stack on the market. It was designed to have ergos like a 1911.
If you're not set on 9mm, Ruger does have their Commander 1911 line out now. It may be a tad over your $700 limit though.
"The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government." - Thomas Jefferson