Battery selection

Hello! Trying to figure out what battery I need for my build. Planning on doing the rifle case built. [Surf n' Destroy] Building a flying sniper rifle case - #33 by superlefax Not comfortable building my own battery, but the Makers of this build said it needs a bunch of power to get started (like 6000w of power). Wondering if I can use 3 of these batteries US $136.32 2% Off | 72V 12Ah 15Ah 20Ah 25Ah 30Ah 40Ah Battery Pack 3000W High Power 84V Electric Bike Motor Electric Scooter Ebike Battery With BMS Or is there someway I can have one built for my needs?

20S is too high considering you are next to it in the water. Better go with 16S, not as bad as 20S and still enough to get the square box out of the water. That seller has bad reviews anyways. Best would be to build ypur own battery or get one from a reputable seller.

Is there any good sellers that have reasonable prices? Also what kind of voltage/ah and max discharge current would you think would work?

Something like this? This 57.6V lithium ion battery pack has a 16S9P configuration with 22.5Ah (amp-hours) capacity and 180A (amps) maximum continuous discharge rating (adjustable)

Also could I order a normal 16s9p battery off AliExpress and remove the bms and replace it with something that allows higher discharge?

You can get 2x8S without BMS and charge them with an RC balancing charger. I got cels from nkon and built my own batteries. I think some people from the forum got some made, you can try to search the forum.