I found an inexpensive car charger for Nokia phones at my local Target store today (Illinois), on final clearance. It was $3.24, marked down from $12.98. It's a "Just Wireless Mobile Swivel Charger". The manufacturer's SKU is 03042, and the UPC is 705954030423. It claims to fit Nokia N80, N91, 770, 3155i, 6101, 6102, 6155i, 6265i, and 6282, but of course also fits the 800 as well. Seems to be reasonably sturdy for a 3rd-party charger. Open circuit voltage is 6.03 volts, vs. 6.17 on the Nokia charger that came with my N800.

I grabbed a couple, and will probably chop off the cord of one to make a USB -> 2mm charger, since I can't find 2mm plugs locally.

It's not available on Target.com, (in-store only) but the link below shows the item.
http://www.target.com/gp/detail.html...sin=B000FMY2JS

P.S. One of the packages was still marked at $6.48, so use the price-checker.