This sounds great; really hoping it takes off. I'm curious: would Beggar's Map work pretty much as-is in other countries, or if not, why not?
I'd suggest making whatever price cutoff you decide on the price for a meal, not a dish. One dish, like a great bowl of tofu stew, can be a meal in itself, but let submitters decide.
Students in college towns are an obvious audience, and I can imagine plenty of low-cost ways to reach out to them and get them to seed the site. Be sure to include Berkeley in your outreach!