I've never purchased a reproduction historic flag, but may in the near future. I would definitely give a nod to Tom Martin's "Piedmont Flag Company" for a couple of reasons. First of all, from the range of flags displayed on his website and from communicating with others, I know Tom has operated a reputable business for quite some time. Also, relying on the comments of others, I know Tom manufactures different grades of flags, ranging from modern manufactured flags, using modern materials for outdoor or heavy use. He also, may rank just below Gideon Flags, for making museum or near-museum quality reproductions. His prices also appear to be reasonable and within the budget of people wanting an historically accurate flag. Finally, I always "push" the books and products of our contributors on the message boards. Tom was one of the first posters on this site and over the life of these message boards has contributed freely to others from his expertise and experience. I've told Tom he could be a little more aggressive with his promotion of his business in connection with his postings, but he does not do so. Before making a purchase, you may want to discuss on this site the level of reproduction flag you might want. Apparently, when you get into the truly authentic reproductions there are some real differences in the offerings from different providers.
Hope that helps.