Jim's sales are epic. No secret club. Open to all.
As noted already, take a look at the Jacks sale thread for some vague details. Jim's M.O... Essentially, a casino goes under, rebrands, sells their chips, etc... Rather than getting destroyed (common), Jim seeks out opportunities to rescue these chips and sell them to the chipping community (at a well deserved profit to him), usually under market value due to crazy volume. Jim is the pro at this, and his efforts have created amazing opportunities to get good chips at reasonable prices (for those who appreciate them). Jim is our hero (the analogy would be a "dealer to a crack addict"...).
These sales have historically broken the internet (with stories of web servers crashing and slow computers).. There also has been those who take advantage of Jim's hard work to make a profit of their own... Flippers circle around these sales to buy up hordes of chips with the intent to immediately flip them to other chippers for big profits. When someone buys tons of the chips, it denies joe-schmoe the opportunity from ordering a set they intended to cherish and put to use... Jim has done a good job limiting the numbers to discourage flippers buying massive hordes for profit (nasty flippers, we hates them we do....).