I'm based in the UK and have just resurrected my Chumby One which died a couple of years ago due to the power supply failing. I followed the advice in Sky123's post:
and purchased a 5V 2A android tablet charger (UK plug) via Ebay. The connector is slimmer that the Chumby One connector, but if you place a small piece of card at the bottom edge of the socket it pushes the small pin upwards and gives a reliable connection. The adapters are priced between £3-£5 so seem a pretty good solution.
Note: I also tried making a temporary power lead by converting a usb lead and attaching the power connector from the original Chumby One power supply. This worked OK connected to a 1.5A USB port on another device, but I wasn't able to charge the back-up battery properly (due to lower power of the USB port I suppose). I didn't have any power supplies with 2A usb ports so wasn't able to fix the battery charging problem. Hence, I tried the android charger instead.