I also have a 2.3, 2.1, 2.0c, 2.0r system. I purchased a woofer as a spare for my 2.3 towers from the eBay seller from France. No problem with shipping and it showed up double - boxed with the speaker in the original box, still taped closed from the factory.
When I got it last year, the seller said they had 16 of them. I haven't seen any come up anywhere else with the correct part number (4dr//51870), and you need that number to match the Ohm rating.
Maybe you can get a bit of a discount on shipping if you get two.
Last edited by Fears4Ears; 09-16-2014 at 03:00 AM.