9000mAh battery though. That's more like it.
9000mAh battery = 460g (according to that page but I'm guessing that includes cables/etc), £102 with CTC discount
or, 3 Portapow battery packs (3400mAh, 120g, £31.50 each) = 10200mAh, 360g, £94.50
But only the Powermonkey Extreme has the 2.1A output that the iPad requires.
For PBP I'm still unsure as to whether I go for a e-Werk or just another Portapow battery pack (each one can do a 600). The chances of me reusing the e-Werk in the next few years is almost none, so it's probably better to hold of buying one until the price has come down or the technology improves slightly. A second Portapow batterypack will be lighter than the e-Werk plus all of the cables too.
Looks like I've just talked myself into another Portapow battery pack.