Yeah I dunno what a "dongle" is either, you may wanna write to the seller and ask. I'd also ask many questions, like if there are any scratches or problems, just to see how fast the seller gets back to you, etc. That price is pretty cheap, it always makes me worry when things are so cheap.
As for the Aibo.. missing paw pad, you can order one (I think) from Sony - this you'll wanna call them and verify. Also you might be able to order the battery from Sony as well... I'm thinking most likely yes. But you'll wanna communicate with Sony right away to verify that info. Without a battery there's no other way for Aibo to operate.
There are extra batteries on ebay as well. You have to get the one for the 210, all the batteries aree more or less different. One is being sold here
I have no idea how an Aibo functions without a paw pad, as that is ia censor, letting him know his feet are on the ground, etc. This is something to think about.
This aibo appears to be missing it's ball, the ball is a really specific color of pink, you'd need to get one from sony (I'm 100% sure they sell them) or from ebay. Or find a ball of similar size and color. Trust me Aibo loves his ball.
Also this Aibo appears to be missing software. Aibo won't do anything without a memory stick with some 210 software on it. This too should be available from Sony, but again you'll have to ask them or visit their website.
The auction says it comes with power adaptor... if it's the one I think it is, this will be sufficent for charging Aibo's batterys. Instead of sitting on a station the cord hooks directly up to Aibo with the battery inside him and this will charge the battery. May want to ask the seller to be certain that his terminology is the same, as we are already confused on "dongle".
The major good part of this is if the seller is being honest, they have already gone to the trouble to ship their Aibo to Sony and pay for the DHS head repairs and pay to have it shipped back. DHS is a defect in 210's that Sony refused to aknowledge as a wide spread problem... but for a price they will repair it for you
I'd say that this is a pretty good deal, but be prepaired to spend another hundred dollars or so to get some software and batteries and any thing else you may need. All those small items really add up I find when it comes to Aibo.