My first USB drive was a 512KB Corsair Voyager about five years ago. More recently, I paid $60 for a 32GB USB 3.0 last year and this year $85 for a 64GB (both ADATA). As my files have increased in size, mostly due to moving up to HD home videos and FRAPS video capturing and editing on gaming, the need for larger and larger capacity USB drives has risen rapidly. I keep the 64GB on my key chain and just pop in a friend's or relative's laptop or PS3 when visiting to show videos and pictures.
But I cannot see paying three times what I paid for the 64GB just to get double capacity. The law of diminishing returns just hit a wall. But as per usual, over time, the price will surely go down. Now the question is, how much bigger can these things get while still holding true to the "thumb" size rule?