Yesterday I went with my son's cub scout den to a Civil War reenactment of the
battle of Cedar Creek. I'd never been to one of these before. It was an interesting view of a culture I'd never seen before. These reenactors spend thousands of dollars to buy their own gear and costumes and they join the battle just for the experience. They don't get paid.
They buy reproductions of period tents and camp the whole weekend using only period camping gear (at least the stuff left out in the open. Maybe they had down sleeping bags and air mattresses inside the tents.)
There are vendors who have larger period tents set up off to the side, and they sell most of the stuff that the reenactors need. So you could just walk up to one of these events and buy everything you need to join in on the fun.