I've ordered this one for a try (it is laptop/usb). 8800maH (32.5Wh) for $75.
http://www.dealextreme.com/details.dx/sku.2283
Mainly for my Cradlepoint EVDO router, but it could recharge my BT headset, n810, and BT gps at the same time, and I can use my laptop chargers.