The Basics:
Uniforms ... $100.00 /kid - more or less depending on style, taste, versions - could go a LOT less if needed (shorts, couple of "basic" tops) just to get the ball rolling, ... a LOT more if hoodies/warm-ups, helmets, bat bags, etc included)
Insurance ... $100-130 /yr (can get a half year for less, but impractical since travel = year round training & competition usually)
Sanction - $20-25 each for NSA & ASA (others?)
Tournaments - $300-400 (more or less, lots of choices) .... note NSA Nationals last year was $600.00!
For 12 player roster:
$1200 (uniforms) + $125 (Insurance) + $45 (Sanction Fees) + $2800 (Tournaments 8 x $350 avg) = $4170.00 in rough costs + $500 (lots of other little things) = $4670
Divided by 12 players = $389 in individual Fees per player at minimum. It will be more than this though, unless you opt for bare bones to get started, with no Nationals
Spano Winter League - add another $850-1000
Special Events?
Team Sponsored Instruction (or Individual)
Hotels, Meals, Travel - Usually on the family's expense and discretion