When I was involved, I had men's pants, and a men's shirt. I didn't find our trading post until after I bought my uniform.
I modified my shirt. The tail was too long and the shirt didn't button up past the small of my waist. I cut the tail down and added a gusset near the bottom. I hemmed the pants, and they were very comfortable.
My daughter worked at Boy Scout camp two summers. She also had men's uniforms.
Our troop had a uniform swap in the spring of the first year my daughter worked at camp. They had men's pants with worn knees. I took them home cut off the pant legs, and hemmed the legs. Free shorts! I think she borrowed a pair of out grown shorts from her brother. I found her shirt at goodwill. I changed the patches on it, and nearly free shirt. The class B (or activity) shirt, and hat were issued to her by the camp.
Remember when looking for gently used uniforms. That an older (not current style) official uniform is still an official uniform, and can be used. The shorts I modified for her were an older style. They looked cute and were slightly different from the rest, but still official.
Remember, when modifying any official uniform. Be conservative, to the point, that no one would know EVER.