FFVII Demo. How rare is it actually?

Tonight while I was organizing a pile of older PS games and sampler disks, I found among them a disk that made me become curious. I do remember owning it, I only have a smallish collection of PS games (maybe 15), but I haven't really played them in years. Anyways, it comes in a white sleeve with a graphic of Cloud on the cover and a list of the contents on the back. I took a couple photos:
http://img79.imageshack.us/img79/866...viidemo2ra.jpg

http://img86.imageshack.us/img86/946...idemobk3jb.jpg

I decided to search for "Final Fantasy VII demo" on Ebay and found one completed auction listing that sold for $51. The seller seemed to make it seem really rare, but I'm wondering if he was blowing it out of proportion or not. Auction link: http://cgi.ebay.com/Final-Fantasy-VI...QQcmdZViewItem

Anybody know about how many copies of it were made? I'm out of the gaming loop now so you guys will have to excuse my ignorance (guitar have taken over as my main hobby... damn expensive just like gaming). I wish I could remember how I got the game in the first place. I remember getting a few of those PS Underground disks in the mail, so maybe from that.