Wambaugh, White & Company strikes me as one of those non-commercial vendors that has to be sought out in order to purchase their wares. In a way, they're a "cult" sutler that authentic reenactors go to. They appear on many group vendors lists, and although a little on the plain side, their Website describes how they make their garments.
WW&C seems to be best known for their Federal garments, and have two selections, JT Martin and Schuylkill Arsenal, to choose from. They do have a Conferate selection consisting of Richmond Depot pattern garments, as well as drawers and civilian shirts. Be mindful that WW&C create their items as per original size requirements, so if you're a larger person, they may not have your size.