The World of Disney store in Downtown Disney used to carry about 4 or 5 different options for wedding bands. At one time I had heard they had discontinued them, but I don't know that for sure.
We bought rings like this, but ended up returning them as they didn't work well on my finger:
I believe there is also a jewelry store in Downtown Disney that had some items, and there may be some items in some of the specialty stores within the parks themselves.
When I was looking for Disney wedding bands, I searched the internet and found nothing...I haven't looked in about 3 years so things could have changed.
If getting to Disney and finding rings isn't an option, consider talking to a local jeweler or goldsmith. They may be able to design something for you!