Are you sure its not Reaper ? In last pages, you had claimed Burraq costs 1/6th of Reaper. A Reaper (in your words advanced Predator) costs 4-5 times of a Predator.
Anyway the question is, how much will a Predator cost in 2020. If in 2010, flyaway cost is $4mill, so acquisition cost of one system should be ~7-10 Mill. The figure should go to ~10-12 million in 2020 due to inflation. Your Burraq would cost $2-3 million. A supposedly cheaper Harpy will cost $1-2 million. 1000 of them will cost $1-2 billion. Take inflation into account and the figure goes to $2-3 billion. Add to this cost of training manpower and associated infrastructure. 1000s of such Harpys will bankrupt your country.