Help with tomato plants wilting

[mick5500]

I bought all these from home depot , some Bonnie and some local organic. I used Miracle grow potting mix and some Kellogg's amend. I am not sure what I am doing wrong. I can dig down in the corner and see down about 10 inches and see if it is dry and need water. I am confused on adding plant food because these say they are self feeding for 90 days and these are all 60 days old. Our temperatures in the high Desert are in the high 80 degrees the last couple weeks.
I sprayed them last week with Natria and have them on blocks with the ground sprayed with insect killer so nothing crawling from below
I have 20 plants in containers and can move them to shade and sun as needed.
Any advice from pictures would be helpful.
Also advice on a good soil tester. I see them for $25.00 on Amazon but local Hydroponics store say a decent PH tester is $75.00

Thank You