Re: I am 35 years-old...is that too old to buy/wear a jersey?
Do what you like. You don't need approval. I was tailgating at the Kentucky game with Ryan Brewer's Dad in Lexington 2 years ago. He had a bunch of Ryan's game worn jerseys. You bet your azz that if he would have let go of one, I'd be wearing it on game day.
The only jersey I own is a #7 UA replica I got Clowney's freshman year. I wear it from time to time... to the office on Fridays in the fall.