Danny (Slugbahr) & I have quite a few sealed discs for sale. Either fully sealed or new discs from multipacks that have been removed from their packets. Lots of Sony Neige, Prism & a few Bianca's. Maxell Twinkle 5-packs or Axia Slim packs. TDK MJ's, Axia 'Select Your Style' 5-packs, Axia J'z etc. Also got some sealed Prime Discs as well.
I've listed some Axia 'Lego' discs on this forum but no-one was interested. So in the end I listed them on eBay. Something I'd rather not do as I hate paying eBay 10% of the sale and then the PayPal fee on top, but it seems the only way to sell things these days.
We're based in Australia and maybe people get put off with paying $13 (USA) - $17(Europe) for postage for a 500g package, yet that's about the same price I'd have to pay to get a similar package sent out of the US or UK these days.
If you're after less generic discs then they are harder to come by these days. The sellers of rare discs on eBay seems to have dried up. Even in the last few years the amount of rare discs around are less. Some discs you may never see for sale (e.g. Benetton, Kenwood etc). Maybe you can find some old collectors who can sell you some spares...