The Aruna map is not cheap (updated a few months ago and is called City Navigator Cambodia V3) and much depends on if you a) live in Cambodia and bought the GPS from Aruna, b) live in Cambodia and imported the GPS or c) live outside in Cambodia and have a GPS. In case a and c, the map will probably cost about 120 USD while in case b the price will be closer to 200 USD.
The CMAG map sounds very interesting and I would love to have a copy even if I would have to pay for it.
A friend of me is working on an update for the map which can be downloaded for free from MapCenter 2. It will include the Cardamom GPS info from "Alrikki" as well as various updates for cities and does have also the tracks from "Harry the Fin" from his Extreme Cambodia Rally early this year (East Cambodia). However, as ususal, he is busy earning a living so it may take some time. Will let you know when it will be uploaded to MapCenter 2.