With regard to the Bedini CD demagnetizer, I had one of these and used it regularly until it broke down for good. I then replaced it with the Acoustic Revive RD-3 which has accomplished essentially the same thing and that being to demagnetize the CD disc itself. The Ayre and Densen discs, however, address the issues within the system as a whole. The Densen Company is still in business but appears to not have this item as part of their product line. Music Direct still has a 'reference version' of this in their on-line catalog but says that the product is no longer available. Given the results I have had with the 'standard version' I would certainly like to get my hands on the 'new and improved' disc.
The Ayre IBE disc is still offered from the manufacturer through their dealer network. The two discs essentially do the same thing but when I'm really motivated, I use them both in combination and I think this does open up the system a bit more.