Here's a pretty useful site: http://www.childrenwithspecialneeds.com/index.p...
Hope this helps, good luck

I made my own. With a color printer, scissors, a laminator, and Velcro strips. My boy uses 2x2 PECs. I found clip art and photos of things on the internet.
I have made them for toys/activities, food, tv shows, colors, etc.
My son is nonverbal an communicates through PECs for everything. Next on my list to do is routine charts.

do2learn has some samples.

If you have a digital camera make your own pictures!! That is what I have done because my son was not connecting the general pic chart to him! Just and idea! :-)

PECS was great when my son was first diagnosed! I have a funny story about pizza and the babysitter: what I called "pizza" was bread, tomato sauce, and cheese baked in the toaster oven. The PECS symbol, however, was a traditional round pizza. One night my son assembled his picture strip to say "[Babysitter], I want pizza, please". She was unaware of the toaster oven concoction and, not knowing what to do otherwise, ordered a pizza from a local delivery place. When I got home I was horrified to think she felt like she needed to order pizza (I reimbursed her, of course). The friend I'd been out with said he wanted one of those magical velcro strips, but with additional options like "beer", "scotch", "steak", etc. ;-)

It was the PECS system that made me realize my son was actually very clever, and the speech was merely trapped inside. Eventually he learned to talk (still not well - he mostly speaks SpongeBob), to the point where some days I long for quiet ;-)

One thing we did was take photos of places we might go; you don't have to have all the pictures the same size. That reminds me....I need to see where I did store away his little book!