I knew several guys who received $500,000 plus years ago. Very few made it.
I knew Carlos Delgato Ryan Freel, Vernon Wells and many others who made it to MLB. I have no idea what their bonuses were. Wells and Delgato were no brainers to get to MLB. Ryan was a great utility player and a great guy. I was some what surprised he made it when I compared him to others that didn't. There are lots of surprises on both sides of the fence.
One SS I watched got a 1.2M bonus and he was one of the worst players I ever saw. He didn't last very long.