I bought one of these on eBay plus a couple of CTA (3rd party) batteries for my K20D, and they have all worked fine:
CTA Mini Battery Charger for Pentax D-LI50 K20D K10D - eBay (item 350086035097 end time Aug-14-08 18:14:03 PDT)
You can't really see it in that picture, but the US-type plug folds into the charger itself, so it's good for traveling -- just a small plastic block with nothing sticking out. The European plug adapter has to sit over the top of that, though. The car adapter has a separate cord that plugs into a jack on the charger block.
(For Lloydy) I can't vouch for how they handle international transactions, but I can say that Cameta shipped promptly to my US address, and the price was pretty good.
No regrets.