I'm only answering this seriously because SuperMillionaire seems to have a little bit of genuine interest in it.

The shake weight is not about lifting. It's about the resistance you get when you shake it. Getting much heavier than it is, and using it 'properly', could actually be pretty dangerous. It is not comparable to picking up a solid object of similar weight and just shaking it. The thing is designed so that the device feels 'heavier' the harder and faster you shake it. Its magnitude of adjustability, based directly on your effort, is something that solid devices just can't do.

I don't think I would have bought it if I saw it was $30 (recall I saw it for $10). After all I knew I wouldn't use it much and $30 can get me things I would want/use more. Just wanted to point out that it's not as pointless as folks here are saying it is.

Of course 'real equipment' and proper gym training or whatever would be better. But those don't cost $30 (or $10) and you generally can't do them while sitting on your couch.