New place opening up it seems... might want to go have a look... just starting out... Home - The Arms Cove Etsy For Gun People? Sure Looks Like It. - Bearing Arms
Very cool but gunbroker.com has been around forever and is the first and most established place as the "eBay for guns". Arms Cove looks promising (and the web graphics and page layout are A+) but I think they're many, many years late to the prom.
