New car?

I got an offer today to buy my aunt's car. She's getting a new one next week. The one she wants to sell me is a 2004 Saturn Vue. (When we bought dave's Saturn Ion in February '05, I said "my next car is going to be a Vue!") It's a v6 AWD, leather, 20,000 miles. Sounds perfect, for $15,500. It's in great condition, and I know where it's been (never been smoked in, never been in an accident, etc.) My car will be paid off in September (or before) and my cousin asked about buying it from me. Both such GREAT offers. It would be SO easy to sell my car to my cousin, and buy my aunt's Vue. BUT, just this week, we decided that when my car gets paid off, we are going to focus on paying off credit card bills and then start banking some money for when the day comes that I go to part-time. You know, the responsible thing. It is not easy to decide between what I want so badly (a new car!) and what I know I should do (live for a while without a car payment...something I've NEVER done before). SO, we're taking the responsible road and not buying her car/selling mine. I may regret not having a great deal on a car I want, but I know that the Vue would cost me so much more in gas. I drive 25 miles each way to work, and my car does pretty well. I have yet to spend $30 to fill-er-up. I know that would be out the window with a Vue.
So, wish me luck in keeping up with what we plan on doing and not buying a new car in the next 2 months!