Associate new Custom Meta-data/Fields with Tags

We are using wordpress for our deals and coupons site. When we started using it, I had very well versed with Custom Taxonomy so ended up using tags for Store Names and today we have around 200-500 stores on our website.

While entering the coupon all the tags are shown in the dropdown and user selects one of the tags to mark the coupon for a particular store.

Now i want to add a URL and a small description for each of the store (which is a tag in this case). Note this is a URL associated to Store/tag NOT Post.

Is there a way we can add Custom Meta data associated to a tag ? Or Do you think there is a better alternative for this ?

Please suggest.

[Moderator Note: No bumping. If it’s that urgent, consider hiring someone instead.]