The Sutlers Stores site is a nice bit of surfing for reenactors who cover multiple periods. This British site is very professionally done, and this place has a multitude of products, many unfamiliar in US reenacting circles. Covered periods include Seven Years War (Regency period), Napoleonic War, American Civil War, American Indian Wars, British Imperial period (including the Boer Wars), WW1, and WW2, as well as the civilian clothing of those periods.
The products on this site, on the whole, are expensive for US-based reenactors. The site on the other hand, is a sight to behold. I recommend giving it a few visits.