It seems that there is one Gold Box SSI release I had never heard of: the Advanced Dungeon's and Dragons: Forgotten Realms Limited Collector's Edition. It's a lovely, hefty box containing Pool of Radiance, Curse of the Azure Bonds and Secret of the Silver Blades, complete with their proper manuals, disks and extras. The compilation was released in 1990 and as far as I know must be pretty rare, though very cheap. You can own it via this Forgotten Realms Limited Collector's Edition eBay auction. Seller ships worldwide.