We've added ArmA2 and ArmA2: Operation Arrowhead to our order page now, at our standard pricing. We are still determining their true resource requirements, which is needed to set a final price.
These games use a ridiculous amount of hard drive space, which will make setup take a bit longer than the few minutes that it typically takes for servers here. New servers should generally be online within around a couple of hours from the signup.
These servers are available on both our normal hosting platform and on managed VPS/VDS/dedicated server machine setups.