I can help you out here!
Peora has affordable jewelry and they have a plus size ring department with sizes between 9-13! Yes!
13!
Here is Size 12..the links to other sizes is on your left hand side.
peora.com/category.aspx?categoryID=367
They also have a site where you can get jewelry for free..just a $5.99 s/h charge. The stuff is constantly changing every 10-15 mins or so and plus sized rings turn up there too.
silverjewelryclub.com/default.aspx
And all their stuff is silver.
Good luck!
ADD: I can't add links yet...I hope just removing the http and www will let it through.