Pretty good summary from like2rake. I just dropped my son off at a D3 (Trinity, Tx) this week, and can more or less confirm what was posted. We are from the West Coast and my son was recruited by a number of Ivy’s, and D1 schools in the West. We really did not explore the D3 option until we got down to decision time and in the end we felt the D3 option was the best match for him from an economic and academic/baseball balance standpoint. He ended up getting more academic money than he was offered athletic at most places, and we were also concerned about the escalating costs in the California Universities which we felt was going to impact our costs in the later years. For whatever reason there was little academic money offered at these schools.
We had a talk with the HC this week and although they take their baseball very seriously at Trinity, they will also work around a players academic schedules more than you will see at a D1. I had not really thought about this, but he said that around 20% of the D3 schools have very serious baseball programs and others, while fielding good teams, do not put the resources into them. You can research all of this at their websites and D3baseball.com to get an idea on the schools baseball program profile in conjunction with the usual academic research tools.
You can also go here to get an idea on how much any school financially supports a program. We found that a there was quite a variation in the financial support of D1 programs also, which also affected how successful they were. Although it was not the primary decision variable for my son it certainly influenced it in wanting to play for a successful program, regardless of the level.
http://ope.ed.gov/athletics/Index.aspx
At least in our case the admissions advisor gave us a pretty good idea on how much money would be offered to him in advance of the official letter of acceptance.
Good Luck!