Actually its an old one. The major issue is "Self Evaluation" meaning the dollar sign that parents and the son himself put on his ability. Scouts will tell you in many suttle ways if you have over valued yourself. They do this because they like the player but realize that the self evaluation has more than likely taken the player off the draft board.
The key thing to look at is this. For example, the player says I will sign for 850 grand and no less or I am going to college. That amount would put the player at about pick 35 to 40 in the area of the draft. So ALL(30) of the TEAMS will have to move that players name card on the draft board over to the unsignable board after those 1st 35 to 40 picks. Then the calls begin while the draft is going on, will you sign for 600, will you sign for 550, will you sign for this and this and this.
If pro baseball and working to become a major league player is the #1 goal and its more important than going to college. Then DO NOT let money get in the way and make you settle for your 2nd option and not what you really wanted to do. If you want to sign, say it. If your not sure and college is what you want, then say it. If its MOSTLY about the money then say it. Then be prepared to go to college. Playing pro baseball and working to become a major league player has to be a passion or you will not stand a chance.