What I did for the Mongolia trip (we needed a week insurance for the UK and Europe part of the trip) was take out a normal insurance policy @ £1200 a year with monthly payments then cancel it and pay the £30 cancellation charge.
If your feeling particularly wily, take out a years cover, use the no quibble 14-day cancellation thing in their T&C to get a refund.
Let us know if you manage it!
But to add to that: DO NOT use 1st Quote insurance
They're bloody rude and inconsiderate.