Unless you're going to use it often, don't go cordless. I had a cordless (no removable battery) dremmel years ago and every time I went to use it, it was dead. I sold it.
I now have a corded one.
Just get the basic one. You don't need all the attachments - it's a waste of money. The main things you'll want are cut-off wheels (and maybe some burrs).
I also have a Makita 9.6 volt "chainsaw sharpener" for times that I need a cordless. It's weak though. There's some kind of circuit breaker that trips momentarily when it heats up. It's a PITA, but you get used to it. What I like about it is that it uses the same batteries as my drill and care opening light, so I've always got (at least) one charged up .