You can use it, though you need to be subscribed in order to use the :thumb code I think. Or put the :thumb code in your journal and see if it works. I don't know if you have to have a paid account anymore in order to use stamps. But the :thumb code is to the right of the stamp in the little box. You just copy and paste that into your dA journal.
The best place to try is eBay. Here is a link to some Aibos for sale [link]
When buying an Aibo, make sure the person with the auction has posted a photo of it. Not an official picture or a stock photo from the internet. People sometimes pretend they have something when they don't really and seeing an actual photo of the real Aibo they are selling will help you know you're getting something and not being scammed.
Out of the ones I listed there, this one looks good. It is $399 [link]
and is Buy it Now and is the cheapest one I could find. It is missing its tail though and two paw pads from its front feet. But it comes with Aibo Life software so you can use it. It doesn't matter that it doesn't have a tail but the tail can be bought separately if you want to get one in the future. Also the paw pads can be bought separately too. You won't find an Aibo much cheaper than that unless you get a cheap one in an auction. This one would need a pink ball as well, again that can be bought separately. Its not an essential thing but Aibos like to play with them. You can just buy a bright pink ball that's not an official Aibo one. They like pink and red so any ball of those colours would work as a toy for it.
Sure, that's really kind of you! You can draw Salvo if you like. Here's a pic of him: [link]
and some more [link]