Jmckelvy -
CPAPs are not cheap! First you need to find out if the cost of your wife's machine will be covered by insurance and if yes, ask which types they provide. If there are options, ask for a model which can run on 110V for home use and 12V for travel. If they won't pay for it or don't offer a 12V option, you will have to decide your next step. Pay for a 12V yourselves or set up your rig to provide 110V for it.
My HMO paid for my machine. I told them that I had to have one which would run on 12V because I spend several months a year in my RV. They provided one, although I had to buy the special 12V cord separately (cpap.com is one vendor; be sure to order the correct cord). I don't know if my machine is the HMO's preferred model or not. I got what I needed and that was what mattered to me.
That said, and with the disclaimer that my machine is 1.5 years old and who knows if they make it anymore, here is what I have:
Phillips Respironics REMstar Auto A-Flex System One 560P
There are more numbers and such on the machine, but I am pretty sure that these are the relevant ones. It also says 12V 6.67A. It is a great machine, no glitches so far. The humidifier detaches, so it can be smaller for travel. It also runs with the humidifier attached and filled with water but no power to its heater.