I may get jumped on for saying this but here goes.

I believe in buying a good commercial kit as a base to work out from.

Many people believe that you should build your own. There are excellent kits out there and the best IMHO are the adventure medical kit series. The rational for contents has already been done for you. I have priced out duplicating such kits and it is not much cheaper if at all. Some items in these kits are hard to find and you maybe forced to buy in bulk quantity (not a bad thing depending).

Get the best you can afford and build on to it as your skill and money allows. Remember; just because you have a kit with items you don't know how to use does not mean someone else who does can't use it.

For example: I wouldn't avoid buying a field surgical kit because I am not qualified to use it. My neighbour is qualified and if I need surgery he has my gear to use. You get the idea.

Bottom line, you need a FA kit. You may only use bandaids/plasters for years out of it and then one day need the whole thing in one go.

Get training! At a minimum I suggest a first responder course
Red Cross, Saint John Ambulance or other.

Again avoid surplus kits. Buy new new new.

Mike