Like the moderator wrote, there is more than enough material AVAILABLE FOR FREE on the internet.
If your interest is Stanitsas, Priggos etc., herein, inside Psaltologion you will find much historically-relevant audio material.
If your interest is in manuscripts attributable to the chant folks you mention, herein in this forum (Psaltologion) you will find more than you probably need, and quite possibly more than your parish priest will ever permit you to use
Especially if you are in the USA
Other excellent sources for audio material are
www.analogion.net,
www.cmkon.org
I smell a scam by those who posted all that material on ebay....Most of the audio material that even Stanitsas' and Priggos' students are aware of is in circulation FREELY. As for Naypliotis' famous 78 rpm discs, they are now available in CD format (
http://www.cmkon.org, scroll to the middle of the page) or you can even find them here inside Psaltologion or
www.analogion.net
NG