When it comes to art fairs, size is everything. How many people attend? How many collectors fly in? How many galleries haul works across continents? How expensive are the booths to rent? How much carbon dioxide is pumped into the atmosphere? These muscular, corporate displays of global commerce, at the largest end, occupy major trade-industry halls, with their utilitarian decor and generic, overpriced food. And yet people come on mass, in the tens-of-thousands. Gargantuan, however, is not the only model in town, as there are fairs for every price-point, and much more room to maneuver and compete among the regional start-ups as companies continue to tap each segment of the market.