Hate to break it to you, mate, but you're not going to find many people who can help you on this forum. It's an international forum and many haven't had the chance to travel to Munich.
The FC Bayern Museum (not "Erlebniswelt", it sounds so commercial

) is a truly great experience and it offers memorabilia from the early days of the club (including its founding days) up until recent successes, including cool gadgets from the recent triple. I'm sure your coin would land in a special "Super Cup" box.
You most certainly do deserve the coin and I find it great that you approached the club first, even if I know plenty of people who loaned souvenirs to the museum at no cost at all.
However, by the end of the day it's a coin supplied by a sponsor and I don't think it has as all too much value. To tell you the truth, I reckon loaning it the museum is a good idea and it'll probably get you more money in the long run (although probably not as much as you might be hoping).
Thanks for your feedback on the Bayern support, by the way. Let me respond with a snide remark: were always better than English support
