Also check with your employer to see if they provide supplemental travel insurance. Mine does and also provides emergency evacuation services. In addition, if you purchase a Spot satellite messenger, you also get SAR and Medevac services from Geos. From what I recall, the rates were pretty reasonable. In addition you can also get travel insurance from Geos/ASUIA.
EDIT: I got a quick quote from the Geos/ASUIA website and an annual multitrip policy is about $160 for an individual. Rates will vary depending on number of people covered and their ages but it does cover multiple trips up to 31 days long for each trip.