Wait, you actually thought he meant going to Wal-Mart and buying 1GB flash drives?
Somehow I doubt that is what the poster meant and you are just building a straw-man argument to gain points.
Insulating, heating and protecting against shock should not be harder for a flash drive than insulating, heating and protecting against impact of a tape drive with lot of moving parts inside.
More practically, I suspect the problem is the amount of time and energy taken to prove and certify a new way of doing things. Flight data recorders are standardised across most of the world and I suspect agreeing and certifing the number/location/design is more difficult than actually changing the hardware.
I believe the cost of installing reliable data drives will be significantly minuscule compared to the actual price of the aircraft and their inherent value of holding extremely valuable data.
