So Seidio launched the thing at $39.95 plus shipping... and it is "25%" longer which I don't believe... but anyhow... it's non-OEM.... but regardless, there are sites like:
BLACKBERRY OEM Battery C-S2
You can get an OEM BB battery for the Curve for $15.... so in effect you can buy 3 additional batteries giving you a total usage time of 400% of the usage of the original battery, not 125% like Siedio is delivering.
People should stop paying $50 for a battery for their cellphone, manufacturers like this make a ton... they spend a tiny amount on R&D because it's just a copy of the OEM, and then mark up a $3 battery to $50 and people fall for it not realizing what a crappy deal it is.
Siedio get with the program, either be innovative (aka more than 25% increase in size, or be price realistic... if you price it at $20 and sell 5000 it's better than pricing it at $50 and selling 500... and since the thing cost you about $3 with distribution and R&D included -- I used to be in the industry, I know this --- you'll be fine and earn more respect and won't be gone in 2 years like every other company who made a battery knock-off to be follow up by 100 less expensive other copies).