Nice find Denob. Very pricey though. You could also plug your current charger into a 100W inverter ($15 on sale at CT) and get the same result. the 100W inverter is as small as the device shown at $62 so I cannot think of a situation where it would be an advantage.

I bought my multi adaptor at Princess Auto. The price was $35, the quality was not so good though they have an excellent return policy. The one I bought has power ratings from 1 volt to 25 volts. My last laptop which fried, used 19 this one uses 20 volts. Make sure you check the power usage/rating on your laptop and power supply before getting one.

Try WalMart, I heard they have a product that is in the $40 range, is not bad and has multi adaptors as well.

The problem with the inverter usage is the amount of power that they draw! Huge difference, my 12v direct plug in can run off the regular car battery for 4 hrs, does not run the batter down to far and the engine will start up, easily and 20 mins of running the battery is fully recharged. The inverter setup, can only be run for 2 hrs or less, it draws substantially more power. Yes it is the cheaper option, though the 100 watt model will not allow this laptop to run, it goes into freak mode when I try. Even the 200 watt inverter did not like this 20 volt laptop, it freaked out as well and shut down. My 400 watt inverter will power this, but it draws the most power to use it.

In the future, I will purchase the 800-1000 watt inverter, it uses the same base power as the 400 watt inverter though it can power so many more appliances that it is well worth the few extra shekels it will cost you.

Right now, I am running directly off the battery in my camper using a battery clip 12v socket directly plugged in 12v adaptor. When I am at an office or other building, I use the supplied 120v power supply, this way the power adaptor I have (which can run on 120 as well, just change the cord on it) gets less usage so it will last longer.
Hope this helps.

edited: try looking online at tigerdirect.ca or .com they had some better quality items as well. Have ordered from them in the past with no problems and they have good return policy as well.

For those looking at inverters, it is well worth understanding the difference between inverters and why sometimes it seems a 200W inverter will not power a 20W device. It all comes down to the type of output the inverter has, the two types I have come across are 'Modified Sine Wave' and 'Full Sine Wave' inverters.

Don't let the name fool you, modified sine wave inverters basically output square waves, if you look at the output on a oscilloscope it doesn't look anything like the output you get from a wall socket. The reason they do this is cost, the electronics are cheap and as a direct result the inverter is cheap. They are fine for running 'basic' devices, they happily run pumps, heaters, most lights etc.

Full sine wave inverters cost a lot more and have complex electronics inside that produce a output that is much closer to the output you expect as 'mains'. They cost a lot more, but sometimes it's worth the investment in a better device.

Now, with no load connected the 200W, 400W and 10kW inverters should all draw pretty much the same (low) power, which is only the parasitic power required to power up the inverter, the reason why any of them may struggle with a laptop charger has to do with the "spikey" way that a laptop charger draws power from the mains, it draws the power in spikes, rather than smoothly across the whole mains cycle. Also, when buying, make sure you look at the continuously rated output the inverter is capable of, rather than the 'instantaneous power' it's similar to how some stereos are rated at gazzilion Watts 'PMPO' when really they have a 35W amplifier IC inside.

One of the downsides of the inverter setup for charging a laptop is that you have a extra efficiency loss when you convert the battery to mains just to convert it back down to 20 ish Volts. The 'laptop inverter' that converts straight from 12 to 20V will be a little bit more efficient overall, but as stated above, a good inverter setup has multiple rather than a single use.

Source: Decade as electronics engineer and spent my uni days working for a electronics retailer selling inverters.

Great advice HeinB and I totally agree with your assessment of modified sine wave vs. pure sine wave inverters. Modified sine wave inverters will power computers and other sensitive electronic equipment however prolonged use will most likely result in damage to the equipment. With many, many years in the computer industry I would never recommend that anyone connect any sensitive electronic equipment to a modified sine wave inverter unless it was a real emergency and for a very short period of time. Modified sine wave inverters are more economical and generally fine where the load is a simple induction load like a motor, or a resistive load like a light bulb. Also not all modified sine wave inverters are created equal and it is generally a case of you get what you pay for.