I don't remember which forum (here or another), but the founder of that website is a collector and the coins for sale are owned by various other collectors who advertise their coins for sale on the site. For each coin listed you'll see the owner's handle and can browse that person's offerings. The founder seemed like a nice guy so I signed up for notifications but there aren't many ancients so I rarely look. It's a nice idea-- sales by collectors for collectors, an alternative to eBay and other such venues. Edited: You can also use the site for your own coin gallery. Looks like I dropped a few coins into a gallery when I signed up. I had forgotten.
I took a look. It's pretty interesting, but it seems a little difficult to find coins for sale. For fun, I typed in 20 cent pieces to see what was for sale but there is no filter function and so I have to go through everyone's collection to find ones for sale. Neat as it is, it seems a little overwhelming.
If you sign up for their emails, you'll get a list of all the new additions. As for anything before that...good luck
