I think the pic came from the slime keychains that were released with Dragon Quest VIII. I think I'll take a picture of my slime keychains and my slime pet later today so you can see them.
The only place I've ever found a slime virtual pet is in Jason's store on ebay. He doesn't have any at the moment in his store (Actually, Apollo just bought the last one because he liked mine so much)
Here's Jason's store (I'm sure you know it but, might as well give it for other people):http://stores.ebay.com/Jasons-Store_Tamagotchis-Other-EPs_W0QQcolZ2QQdirZQ2d1QQfsubZ20QQftidZ2QQpZ2QQtZkm
You could probably message him to see if he would sell you one even though they aren't in the store at the moment... He did that for my mom once. I can't remember the exact price but it was under $30... I wanna say it was $18 but maybe I'm wrong
I suggest this pet for any hardcore tamagotchi fans because it's so unique