Tinting porch/floor paint myself?

Some paint companies sell little sample jars but they're pretty small and usually for walls. You can often buy the tubes of colour to tint paint though they're not cheap and not available everywhere. You can tint latex paint with acrylic craft paint. But you say you want to use bright colours, and those may be hard to get if you're starting with a white base. It takes a great deal of pigment to get a bright colour. If you start with a deep base you'll have better luck but I still think you'll have trouble getting bright colours tinting paint yourself. If this was for a wall, you could use the acrylic craft paints but I doubt they would stand up to wear on a floor unless you put a clear floor-grade glaze on it, and even then...? What you save on buying paint you would spend on acrylics and glaze.

If you have a Habitat for Humanity store near you, see if they have any bright colours but remember you need floor paint, and people rarely paint floors in bright colours. You could check the big stores and paint stores for mistints.

If I were you, I'd settle on four colours for the spattering and stencilling, buy a quart of each, and plan for colours that you can change a bit with the acrylic paints or with tubes of pigment. I don't know what colours you have in mind, but if you got a quart each of red, blue, yellow and perhaps green, deep colours as close to the true pigments as possible(go to a good paint store so they'll know what you're talking about), and if you have some white as well, you will be able to make a pretty good range of colour with those. You could use those colours by themselves or alter them a bit by mixing with the others. If you don't know what colours mix with what to make others, search 'colour mixing' online and you'll find advice about how to make colours. Start small if you're mixing paint; it's too easy to get too much of a colour you won't use anywhere else, and always add to the white rather than to the colour because it takes so much white to change a colour. When you have a colour you like, put a sample of it on a piece of paper, in case you want more of it sometime.

i would have a look at some paint charts pick a colour that has a white base and go to your local hardeware shop and ask if they could give you the amount of tint in a cup and then mix it doing this you will be able to match the paint if you need to touch up anywhere as when you mix one paint with another it is too hard to match up in the future or if you require more paint to finish the job tint is a different product from paint and if you want to do it properly buy the tint to add to your paint dont mix other paint in with what you have good luck i am sure your local store can help you with this

buy tubes of acrylic artist paint at an art store, get student grade and it will be cheap