$300 is not bad at all if the condition is acceptable, and no way would I think that's the BB price of the 'reissues' (which should be much higher it seems to me), so even if the year-listing mistakenly confused the two, the price-listing probably didn't.
I do recall seeing somewhere that many owners have upgraded caps and wiring and such, even installing binding posts, but I have no personal experience with these mods, do a search (Web not Agon) and you might find something.
As for finding original replacement drivers, the same or very similar drivers were also used in some later, less costly models of the original Allison company that sold in larger quantities, such as the "CD_#" model line. (Mids and tweeters would probably be easier to locate, since most of the woofers used in these smaller model were less than 10".) As I recall there was actually a second ownership of the original company, consecutive with Roy Allison's ownership, that continued to use the same in-house drivers for those models that featured them. Then that company eventually went defunct, and later the 'reissue' company or whatever you want to call it was started by yet a third ownership, but those speakers shared no parts with the originals and used conventional OEM drivers. The original firm also came out with a fancier, 'new and improved' successor model to the Ones, that expanded on the same core design principles, called the IC-20 ("IC" stood for Image Control).
I do recall seeing somewhere that many owners have upgraded caps and wiring and such, even installing binding posts, but I have no personal experience with these mods, do a search (Web not Agon) and you might find something.
As for finding original replacement drivers, the same or very similar drivers were also used in some later, less costly models of the original Allison company that sold in larger quantities, such as the "CD_#" model line. (Mids and tweeters would probably be easier to locate, since most of the woofers used in these smaller model were less than 10".) As I recall there was actually a second ownership of the original company, consecutive with Roy Allison's ownership, that continued to use the same in-house drivers for those models that featured them. Then that company eventually went defunct, and later the 'reissue' company or whatever you want to call it was started by yet a third ownership, but those speakers shared no parts with the originals and used conventional OEM drivers. The original firm also came out with a fancier, 'new and improved' successor model to the Ones, that expanded on the same core design principles, called the IC-20 ("IC" stood for Image Control).