That indeed must be the most difficult descision developers have to make: pricing. If they had a team of 15 working on it for 9 months @ 50k/year that could cost (over here, in NL):
50,000 x 1.6 (about the overhead costs for employers) x 15 / 12 x 9 = $900,000. Charging $80 would require 11,250 downloads. Charging $2,99 comes to 300M purchases. Excluding hardware, dev license, offices, photo & video equipment and and all that jazz.
Purely speculating here, obviously.