you are lucky, we have wild grapes around here but they have NO flavor. I do love making jelly with blackberries or apples/crabapples.
Here is a tip, I keep a ziploc bag in my freezer all year, when I cut up apples for something, I throw the cores in the bag. When I make blackberry jelly, I put the apple cores in and cook it all together. Adds pectin and makes the jelly jell. I don't like to spend any more money than I have to.