I have dealt with Brad Koda(Best) and Bruce Carso(B&C) for decades. Steve Cohen(Wizztronics), Bruce Carso and Brad Koda bought out Atari's inventory when Atari shut down. Steve Cohen is out of the picture these days, leaving Best and B&C owning almost 100% of new in box Atari products and parts. Bruce pretty much sells only on Ebay, leaving Bradley the only one doing direct sales. If you can catch Bruce on the phone, he will sell to you, but that's a challenge these days. Brad is basically the Sole vendor on planet earth. If you establish rapport with Brad you'll always get what you need. He likes e-mail sales of quantities less than 4 items. Remember he does not have to sell another thing and he is still set financially. I have had nothing but good experiences with Best Electronics. Always got fast shipping, well packed and in perfect shape at a reasonable price.
ST freekz and Atarimax may have Atari LSI chips too.