Snails feeding on my broccoli,...

Since I sowed the Brassicaceae- Cabbage, Cauliflower & Broccoli I have been checking them for snails & slugs. After last year's experience I bought Copper wire netting from Lee Valley and nailed it to the sides of the bed. Since it is expensive I tried this for only one bed. I nailed some left over wire to a side of the second bed where I sowed Broccoli. The plan was to thin them after they grew a few inches high. It's here the leaves have been eaten. 

 

 Found the culprits - two snails. I crushed some egg shells, which I have been saving for my Tomato transplants, and spread around the seedlings & covered with milk cans. Will check to see if it's effective. 
Later in the evening went to Rona & Home Depot to find diatomaceous earth. Seems they have no clue what it is and I had to explain the purpose. Both stores assured they'd procure this product. Probably I might have to check at a local nursery if the egg shells doesn't work.