A good first aid kit does not have to be large or expensive. Take a moment to watch the attached video and see what I mean.
The basic things that you need in a basic first aid kit are:
Gauze in several different sizes
Band aids ( don't forget to get character ones for the kids)
1st aid or triple antibiotic cream
Ace bandage or vet wrap
And of course something like a large Ziploc bag or a fishing tackle box to keep everything in!
All the parts of a kit like this can easily be bought at your local Dollar Tree and run you all total under $20!
Keep your kit in an accessible location and consider making a kit like this for each member of your household and one for your car.