You only need "that gal" and Stay Don't Stray for the ingredients.
Twist some "that gal" and add a pump of Stay Don't Stray, blend them, and you will get your very own BB Cream.
If you want a healthy glow complexion, add some High Beam to your BB Cream concoction.
Because High Beam's texture is pearly white base, you only need to add a little. If you already have Girl Meets Pearl (which is sister to "that gal" but with a little shimmer), the you can blend it straight away with Stay Don't Stray to create that glowing BB Cream.
Remember in the review of Stay Don't Stray I also mentioned that it is rumored made out of Boi-ing and Lemon Aid...
Well, if you have Boi-ing and Lemon Aid then try blend them together to make your own Stay Don't Stray.
Anyway, if you're concern of your spending, these are all you need:
To make things easier for you, I will list down the chemistry equation how you can make up your own Benefit product without having to buy everything:
Stay Don't Stray = Boi-ing + Lemon Aid
BB Cream = that gal + Stay Don't Stray
BB Cream = that gal + (Boi-ing + Lemon Aid)
Girl Meets Pearl = that gal + High Beam
BB Cream with glow = Girl Meets Pearl + Stay Don't Stray
BB Cream with glow = (that gal + High Beam) + Stay Don't Stray
BB Cream with glow = (that gal + High Beam) + (Boi-ing+Lemon Aid)
If you have any of the products, go play with it. It's really fun. In terms of how much to put, that really depends on your skin complexion. If you have darker skin then add more of the darker shade products and vice versa.
I hope these tips are useful to you. Meanwhile, I will go through all my makeups and see if I can create anything out of the stuff I already have.