Here's my $.02 worth (remember . . . worth exactly what you paid for it)
You need a 6-pac license to legally take paying customers on a vessel. And, you won't get insurance without it. I think it was $900 last I checked.
Coming in at $100 is NOT going to endear you to other captains locally. Speaking for myself, I'd want to introduce myself to the other local captains, offer to take up the slack if they got overbooked. Then start in earnest.
Basically, work it out. Not proposing anything unethical like price fixing. But when I've chartered along the coast, the best captains worked together so their clients were on fish, and I could get out if there was a scheduling conflict (happens all the time). If you're undercutting everyone as the "new guy" I'm not sure you're going to get the call back on the question of "seen the stripers"?
Lonely coming in with sunburned customers and zero fish while others are laughing and having a good time with full coolers.
OK, don't mean to be a downer; like I said, just my $.02.