Where to get a simple, cheep pavilion - RonO's Ramblings
In looking for pavilions to merchant out of, period appearance and easy setup tend to be on opposite ends of the spectrum, in my experience. Throwing in "not too expensive" makes it even harder to move to the period appearance end of the spectrum.
For maximum ease of setup, an EZ-Up style (ezup.com, if you're not sure what I'm talking about) are the winners, IMO. We've got three. They're pretty common around here, and adding your own additional cover to make it more period-ish is also pretty common (I don't). They are, however, on the heavy and bulky end of the spectrum. A real EZ-Up or one of this style from Powell & Powell (kingcanopy.com) are not cheap, but are more durable than the cheap knock-offs.
Most period is easy - Pather Pavillions, and the like. But not cheap or as easy to set up as some modern things.
Cheapest are the things with sectional tubular legs and plasticy separate one-piece covers. They aren't too heavy or too bad to put up, but they aren't exactly pretty, even for a mundane event. And I don't tell you, as a Scout, how, they'd hold up to real Weather.
For the ultra-portable-easy-light, check out some of the shade fly things from L.L. Bean and such. Shock-corded poles, etc. But very very modern, no disguising those babies.