4D reamer rentals. Chamber reamers for most calibers, reasonable rates. A lot cheaper than buying a reamer you'll only use once. All tools are inspected and sharpened (as needed) when returned. Yes, I have used them several times and was very pleased. http://www.4-dproducts.com/
Track of the Wolf, mostly M/L supplies but some breech loading gun stuff as well, liners by the inch, barrels, wood and furniture. http://www.trackofthewolf.com/(S(hdnmbu55nxstkenqoxjclr55))/index.aspx
Kebco, ocassionally some nice European guns and items. Good guy to deal with. http://www.kebcollc.com/
Dixie Gun WOrks, like Track of the wolf mostly M/L stuff but a WIDE range of other products as well. http://www.dixiegunworks.com/product_info.php?products_id=7362
Peter Dyson, various parts. http://www.peterdyson.co.uk/acatalog/sitemap.html