Set items are hard to price. If I were to look at that ring's stat's I would say it sucks. People will pay more though because it's a set item. Looking at other similar stat items on the AH though can be a crap shoot because other people think because it's green to charge 10x what they normally would, and their stuff never sells. I am currently trying to sell an IK chestpiece that rolled decent stats. When I search the AH for similar stat items the lowest is going for 200 mil. I put mine up for roughly 2/3 of that, and I am having a hard time selling it. When in doubt search the AH for items with the same stats, price match or slightly undercut them, and let it ride to see what happens. If it doesn't sell D3 keeps a log of your items and whether or not they sold/price/etc, so adjust down accordingly.