You should spend more time searching the forums for leasing tips and reading leasing 101 on the main site.
With that said, you were never going to get a good deal on a used CTS - V for leasing.
Used cars generally lease horrifically because they are not financed by the primary manufacturer captive, they are financed by third party banks with low residual values (yours is quoted with a decent 56%, however) and high money factors.
Generally, we advise against leasing used cars. You are better off financing for 60 months and likely coming out ahead on it.
That is not a good measure of a realistic deal. Your best bet is checking out the “Shared Deals” section.
IMO, I would not bother leasing a used car. Why the CTS? Have you driven one?
If that is your budget, there are a lot other brands in that price range. I would suggest checking out the “Marketplace”.