shop.stackexchange.com and was really excited when I saw that I might be able to purchase shirts and things like that with my reputation! But to no avail.
Has this been talked about? I'd love to make purchases with my rep.
Placing monetary value on reputation is going to be a big mistake. Where is the profit in it for SE?
Reputation is an arbitrary number which is based on how other people rate your contributions to a site, it does not, in any way, represent any monetary value, or any other value for that matter outside of SE.
Seriously, why not just support SE for providing you excellent Q&A site by actually purchasing something from the store?