Agree with what CD said "If you stay in college four years, unless you are a very high draft choice, the money is almost nil". Take a look at the numbers below - these are from the top 10 rounds (1-10) of the 2009 MLB draft. I think 14 (of the 22 seniors) got 40k or less - and don't forget, these are top ten round guys...
4 yr college (juniors)
avg(median) $155,700
avg(mode) $125,000
avg(mean) $475,254
min $60,000
max $7,500,000
How many drafted & signed 145
4 yr college(seniors)
avg(median) $35,000
avg(mode) $25,000
avg(mean) $69,109
min $10,000
max $200,000
How many drafted&signed 22
juco
avg(median) $137,500
avg(mode) $125,000
avg(mean) $201,459
min $90,000
max $475,000
How many drafted & signed 22
High school
avg(median) $500,000
avg(mode) $125,000
avg(mean) $810,239
min $70,000
max $6,250,000
How many drafted & signed 97