Best Buy sells a 4' Insignia branded one, I picked one up when I needed a spare charger, seems to do pretty well (meaning I can't tell any difference in the capabilities of it). The platform is larger than the OEM charger though.
Here is a link to it.
Did they start putting the short 1m cable in the box? The original puck I got with my first watch is still going strong, that cable seemed to go on forever.