I know each Dollar-style store is different, but you may want to check it out because I saw some beautiful bug nets and kits at the Dollar Tree the other day.
And if you can't find magnifying glasses, check out your local office supply store. They're usually near the marker/pen area (I had to get one for my costume and couldn't find them anywhere else -- not even at Walmart or Target). While you're there, you can buy a little mini spiral pad for the bug journal, a ruler, and index cards.
If you fear your child may harm the bugs, you could instead make a leaf identifying kit. You could still include the net; just have them stick their leaves in the net, imagining that they are capturing them. They can even trace the leaves in the journal. :flower: