Wish I knew someplace good to buy single-stage paint economically

The problem is the state you live in. A whole different set of rules there for what they can sell and have shipped in.
Yep, I suggested Kirker before but now that I see it is for California, it may put you into a 2 stage which you did not want. The Black Diamond is a low VOC but a 2 stage, not sure about their other paints. You would need to look at the VOC information for whatever you buy.