Funny, I was just talking with a friend last night about the viability of a cheese sandwich cart/stall in NYC. They're extremely cheap to produce (plain wheat bread and Kraft singles) and when hot, are delicious snacks. I was thinking of a price point closer to $1, since you can easily get so much food in the city for around $5 (gyros, chicken w/ rice, etc). Interesting to see someone doing it already!