Using this one:
http://www.amazon.com/BESTEK%C2%AE-Inverter-Adapter-Cigarette-Red-coffee/dp/B00U71XJ0K/ref=sr_1_5?ie=UTF8&qid=1434343949&sr=8-5&keywords=bestek+200w
Though it was less than $20 a month ago.
This one's much nicer to look at (and cheaper as of this moment) but you only have one...