Is it a good idea to buy a substitute battery ?

I had been long wondering how are these subsitute batteries that you can find all around the web and why there are so cheap compared to the laptop constructor ones.
I was affraid about the quality, the design and even the safety.
I often buy substitute ink for my printer, but that is not exactly the same kind of thing nor the same price.

But my need overpassed my fears.

I found one rather cheap on this website. I mean much cheaper than the one from Sony, which was around 300 € !!! And this is always very expensive whatever the brand is.
At this price, it is better to buy a new laptop (maybe that’s what they aim).

I chose the one with a bigger power and payed with paypal. Surprisingly, I received it quickly, just two days after my purchase.

Concerning the quality of this battery, so far, I am very happy. Over my expectations. The design exactly look like the Sony one. I guess it just come out from the same factory but doesn’t have the Sony stick…

This new battery has 7200 mAh and offers me about 4h30 of work on battery ! To be compared with the 2h30 I had with the original one (and only 1h more recently).

So, don’t be affraid anymore to buy no-name replacement batteries !
I will definitely so in the future, when I need.