Orca Design is THE US parts division of JMLabs, the maker of Focal drivers. Go to their website(orcadesign.com) for a list of dealers. I like Madisound, but Zalytron is good once you get over the initial hump of dealing with Elliot for the first time(not very polite to first time callers - you have to become a customer for him to open up, but his real world knowledge is immense). The 12" Focal driver is excellent, but very expensive. European(some companies such as Vifa and Peerless excepted) drivers larger than 8" tend to be quite exhorbitant in the area of price. Usually, the larger Focal woofers do better in vented boxes, but you would be OK. I suggest you contact Audio4fun. If you can get a nice deal on those Dynaudio woofers, you will NOT be able to match them for the money. Be sure to check the model number, to make sure it is OK(correct impedence, etc.) for your speaker. If you find the prices of these Euro woofers are too high for you, the best domestic woofers for sealed box configurations are from Audio Concepts(ACI). Their woofers are designed for sealed enclosure applications; their features are most suited for this type of use than almost anything else you can find. Not sure of the current prices(should be a fraction of the Euro drivers), but you absolutely cannot do better for the money for this application. Please also consider the crossover parts and wire. Being that you have been using drivers of such high quality, the OEM Infinity parts will SERIOUSLY hold you back. You need to go up at least two levels of quality to realize the potential of your drivers. Feel free to discuss this area in greater depth, as I can give you the sources for this stuff. Good luck!