I own four. An Ers 210 an Ers311, an ERS312 and an ERS 31L. I'm not rich, just dedicated and a bit stupid. Scratch that, REALLY stupid.
Aibos are fun for awhile, but the more time you spend with them, the more you notice how repetitive they are. They do a lot, but eventually their tricks get very repetitive and really dull.
And Sony isn't really that supportive.If a new model comes out, you're fucked because they will drop support of the last model like a hot potatoe. Software for any model than the latest is near impossible to find.And they break if you so much as fart in their general direction.
Really they aren't that much more interesting than your average Furby.If you're a hacker type and enjoy programming you might get more out of them than I did.But that's the only way I could really reccommend them. They aren't really replacement pets, just very expensive toys.