Answer:
Buy your self a long dress coat from a thrift store and a lot of material from a fabric store. Also, getting a few jeans buttons. Try getting one made of virgin wool preferably. As for the breeches, get some baggy dress pants and try making laces (like on a shoe or corset) on the bottom half (by the calf's). As for the boots... You are on your own for that one. Try eBay or an army surplus for the boots and hat. I would also recommend looking up a picture while making it.