I'm all for the "buy while you're young" argument, but of course, sometimes reality bites you in the ass.
I always used to go by the three hundred dollar rule--if the car payments would end up being over $300 a month, then the car was unaffordable for me as I had too many other things I wanted to do in life.
If the car keeps you from doing the other things you want to do, it's not worth it. So, just factor in maintenance, insurance, payments and decide for yourself.
Oh, but what's all this talk about enjoying the car before you get older and won't be able to!? There will always be time for sports cars, no matter what decade you're in--no need to make excuses!