Buy small order at Sherwin Williams, then you'll get 2 for 1 offer in email on gallons of paint. I just doubled up on my exterior SuperPaint primer and paint in one. I did use separate primer for bare wood though.
LOL, 5Gal of GOOD paint is going to be next shocker. Sherwin Williams runs occasional great deals and I was able to get some at 45% off. Sign up for offers. Spraying will use it up fast. I sprayed a couple doors and was amazed how fast it goes away.