There are a number of online retailers that can sell you reproduction tunics (the coat) and breeches (the pants). As has been said previously, the uniforms are expensive to most people's budgets. My troop turned 100 in 2017. I actually had been working on a "centennial" uniform for a few years prior to that. Here's me wearing it back in 2017, flooded by a picture of the tunic closer up.
I recommend the US army M1912 tunic in the summer cotton fabric instead of the more expensive, heavier, and probably scratchier wool fabric. The tunic and breeches will probably cost about $350 as a