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

Jim Lusk said
Right here and will ship to you. I've used their paint and it seems ok. It's not best quality, but it will work. I have their midnight blue for my Barracuda convertible.

Also, at one time (not sure how it is today) you could still get Imron and Centari from boat dealers here in California...

Restoration Shop

Jim hit the nail ON THE HEAD! I have been buying paint, primer and body work supplies from TCP Global (Restoration shop is their name for their paints) for a long time. They have a line of 'their' colors plus they will mix pretty much any color for any car ever made. Just enter year and make and you will see paint options and prices. I painted my 69 Cuda with their base/clear paint. I find that it sprays, covers and polishes out as nicely as any paint I have ever used.