?What's an affordable (under $10 per bottle) wine for aging (for about 7 years.)

My family is making a time capsule, and we plan on opening it in 7 years. We thought it would be fun to get some wine, write reviews of it, and put the reviews in the time capsule; then put the wine in the cellar for 7 years, and taste the wine when we open our time capsule to see how it aged. We don’t want to go over $10 a bottle. It doesn’t need to be a really great wine or anything—we’re not connoisseurs—we just want something that will probably improve or stay the same, rather than degrade in seven years’ time.