I made a stop in Roswell New Mexico a while back. It was a bit different than I thought it would be. There weren't green men on every corner nor was it overly done. Just a regular town with a different history.
I did stop at the Alien Museum and took the tour which was pretty interesting. I also stopped by the gift shop on my way out. I found a t-shirt that had potential and for some reason I put it back. I'm not sure why I did that but later that night and far away from Roswell I discovered that I did not purchase that t-shirt. Silly me. So I didn't follow my own advice and take the t-shirt with me to the counter. I could have decided at the last minute that I didn't want the shirt but I got side tracked and didn't have it with me to even try. So now I'm out a souvenir that I was going to use as a gift.
So I guess I need to try and follow my own advice a bit more. So I guess the modification to my souvenir buying tip is if you see something interesting carry it around with you. I still think you should buy any souvenir that you find interesting. It may come back to haunt you just like it did me.