I don't know about a 507, but Todd the Vinyl and Headphone Junkie has a used Meridian 588 posted on his site. He also is a dealer for both the Meridian G07 and G08. Give him a call, or send him an e-mail though his website.
Also look around for the older Meridian 508.20 or 508.24 CD players. I had the 508 for about a year and a half and it was just an amazing player. Since it's an older model, the prices are very low. The digital components aren't as up-to-date as those on the newer players, but analogue technology hasn't improved so much -- sonically speaking, anyway. You obviously can't get a new player but they're built very well and Meridian is usually very good about fixing their players if they malfunction.
I can't comment on how the Meridian compares to the newer models. I did hear the 588 a few years back but that was before I had my 508 and it was not in a familiar rig.