Am former 91B4S, US Army Special Forces Senior Medical NCO, and EMT-D (NYS) with local volunteer Fire Co. FIRST thing you have to do is EDUCATE yourself about what the HoHa you’re capable of doing. If you KNEW what you were doing, you would not need to ask others what should be in your kit. Lack of medical knowledge is ultimately a danger to you, and everyone who may depend on you and your “KIT”, a killer. Take a first rate, first aid course, including CPR. Then put the kit together yourself, ‘cause you’ll KNOW what your capabilities are, and what you need. $650 for a kit is bizarrely expensive. Spend some on a good med course, some on a good bag, and the rest as KNOWLEDGE dictates. I’d tell you what I carried, but what’s the use, as you don’t know how to use it. Get EDUCATED FIRST!!!
Get trained first. Otherwise, you risk doing more harm than good.