There are some reassonably priced clothes available by mail order for the 1810 to 1835 time period. Broad fall pants and a shirt will run you about 45 bucks from Gohn Bros out of Middlebury Indiana. You can cut suspenders out of leather and get a pair of leather wellington boots (not cowboy boots) It is an Amish mail orderr house. I have used their broadfall pants at rendezvous for 20 years. They even sell the pants in natural cotton color without buttons if you want to add your own antler buttons. Not really Colonial longhunter clothes, but certainly correct for a slightly later period. Gohn Bros is one of the few places that sells Osnaburg, a home spun linen looking material. Proper for a Rifleman's frock.
At some of the larger rendezvous, like the one coming up in May at Muddy Run Park in Lancaster County, folks put out trade blankets, and swap off clothes they or the kids have outgrown. Not a bad place to pick up some stuff.
At the really big get togethers like Ft Frederick's Market Fair, there will be several vendor's selling more Colonial appropriate clothes. But be prepared to pay$. Nearly every rural area has a few women who will do alterations and sewing for others. If all else fails order a pattern and hire such a woman to sew the outfit for you.
As a thoroughly last resort, track down your granndma and have her teach you to sew. (I got my dear MIL to show me.)
Several mail order outfits sell patterns. There are historically correct patterns and costume patterns. (Like a theater company would use just to get the look. ) either should do, although the costume patterns are probably easier.