Celebration does have a market street. If you check the link below it will tell you about the shopping and dining etc.
http://www.celebrationtowncenter.com/ee/
We normally go at least once on during our holiday, and normally do that on a Sunday morning as that is when the Farmers Market is on - lots of stalls selling local crafts and produce (honey, moisturisers, candles etc).
For food we like the Market Street Cafe. It has a good menu, reasonable prices and the views across the lake are nice too.