In my relatively short experience, it's best to stick with Joye's atties. I've gotten a couple that I'm pretty sure were not Joyes, and their bridges were significantly wider--to the point that carts melted a little too easily. I had one recently that I had to flood to get a decent (not burnt) flavor out of. MyPVshop.com ships atties in the original Joye boxes and ships free after about $50. Check out their atty bundles, too: five for the price of four.
Hope this helped.
JD