I have used Dixie Gun Works in the past and been very satisfied with the results. I have always thought the guns were a little pricy, however the parts and accessories have been fair enough. You can find some good scratch and dent deals if you go there in person! I'm also satisfied with Track of the Wolf, Pecatonica River, Rice Barrels Company, Green Mountain Barrel Company and Graf and Sons; all have provided great service and conversation on the phone. Grafs had a warning on their website that orders would take some time to fill (weeks at the time) and the last powder order I purchased early this year was just that...weeks to fill. Dixie has put a similar warning on their website, maybe it wasn't there at the time some folks placed their orders, but its there now. I typically don't mind the wait as long as we have been made aware of it, extremely frustrating with no warning. Still waiting on two hydraulic hoses that were "in stock" for the backhoe, ordered the parts 3 weeks ago, when I called they said it would be another two weeks...
Last couple orders I have placed was with "The Gun Works" muzzleloader Emporium. I needed a breech plug to convert a T/C barrel to flintlock and Track of the Wolf didn't have the size I needed in stock and The Gun Works did so I tried them out. Next time I wanted some various parts and spring vise, they called me to verify the order as the spring vice wasn't going to work on the coil spring lock parts I ordered. We had a good conversation and I assured them I needed the vise for other locks with flat springs. I thought it was good of them to check out the order and give me a call to make sure it was correct. Shipping was just over a week, but most of that time was on me as I sent them a personal check as payment. Their website / ordering system is a little old school compared to some, so is their customer service...old school in a good way! If you are unhappy with your current supplier or they don't have the parts your looking for, give The Gun Works a try!