Let's see... I suppose the best thing to sell is something that you use all the time and/or spend way too much money on so that you can maximally enjoy all the freebies.
In that case, I'd love to have a little corner health-food cafe. And the big ticket item would be frozen yogurt-- and by frozen yogurt, I mean *real yogurt* that is frozen. Some yummy vegetarian sandwiches might be in order too. Oh yeah, and chai!! Coffee can come too.