You are absolutely NOT too old! And I am not convinced you need an MBA to start your OWN business (my advice would be different if you were looking to work within a large fashion company).
Why not start on your own? Design and make one or two items - take photos - Sell them YOURSELF online (Etsy or one of those sites). Have your friends take pics wearing your stuff and post them on Facebook/MySpace or other sites). Understand that this may lead to people stealing your design idea (You can do an online search to see how you can protect your ideas.)
Remember - the two guys that started the "Life is Good" T-shirts did it by selling those tee shirts at concerts. Look up their story. You can start in a similar way.
You can do whatever you put your mind to. Listen only to people who believe in you - you are young enough to take risks! Go for it.
mhalligan@advantedgesales.com