The one I have now grow from 2" to 6" in the first year. And another 2" the second year. I've had him for over 3 years now and he's about 8.5" You can get a lot of growth within the first year, but seemed to slow down after that.
Yea at least around here all the big ones iv seen on fuana and king snake even at a few shows have all been right around 2-300 bucks but all the small ones i see haven't been no more than 20-30 bucks.
Technically...if you were to look at the times he's been awake, he's probably grown to 8.5" in less than 2 years. I let him hibernate during the winter months. He's only awake 7-9 months out of the year. This is a picture of him his second year before hibernation.