If she is a very close and dear friend a gift would be appropriate. That being said, if I ever made a double wedding ring I'd have a very hard time parting with it. I bought a dwr quilt because I knew I'd probably never make one.
Look at the old country store and check out their prices. They run from $600 - $1000+ for a dwr.
Here's one similar to yours.
http://www.theoldcountrystore.com/qu...ng&col1=&col2=