Our family (4) are making our first trip to AC next week too. Here's a list in no particular order that I created doing searches on this forum in preparation for my trip:
1. Hill Gonzales (at Chuck & Robbie's dock)
2. Grumpy & Happy
3. Lil' Alphonse
4. Searious Adventures
5. Elbert at White Sands Dive Shop
Prices vary widely, depending on whether you want 1/2-day or full-day, and shared or private charter. I'm budgeting $40-50 per person + park fees + $10 pp for equipment rental. I plan to negotiate best deal in person after I get there. Good luck. Maybe we'll wind up sharing a boat!