What's the difference between those branded battery grip from canon compared to those unnamed one?

i was contemplating of buying a battery grip for my canon D40. however the canon is so expensive compared to those unnamed brands. i just need your thoughts and comparison regarding these options. branded or unnamed battery grip. your opinion!

An officially branded battery grip may have better ergonomics and a higher resale value down the road, should you choose to sell it later.

Although I do not specifically have experience with off-brand battery grips, I have tried off-brand flash, omnibounce, remote shutter switches, a lightsphere-like diffuser, tamron and sigma lenses.

I have yet to experience any issues or problems with any of those items.

Take a look at these:

http://www.dealextreme.com/details.dx/sku.11229

http://www.dealextreme.com/details.dx/sku.15274

http://www.dealextreme.com/details.dx/sku.12487

It depends, some people are perfectly happy with there third party grips. I went with Canon because I read a lot of reviews that mentioned that the shutter button on third party grips felt mushy and not quite as nice. In the end Im sure the third party grips work fine and its mostly a matter of aesthetics and just wanting Canon components. Yes its a cheap peace of plastic and not worth the price they charge, but I figure that if Canon is building this thing cheaply, the third party versions can only get worse.