From a collector's standpoint, it's not a bad investment. It's extremely difficult to get an entire band's autograph on one item. This is something you know is legitimate, even if there hundreds/thousands of them. I've seen items autographed by Jon alone selling for $300 and they had nothing to prove it was real!
In 20 years it will be worth more than $100, you can bet. If you put it on Ebay right now you could get moer than $100 because there are people who would want it who can't get to a concert to buy it.
There is NO reason to feel guilty about buying one.
Just enjoy it and tell your kids they can make a profit one day.
Becky