I have bought Baltic Birch Plywood from Woodworkers Source and other vendors before. No matter where you get it there are always some issues with warping because it's so thin. However, this batch was especially problematic. The cost is reasonable but expect that not all pieces will be usable in your laser cutter. I used hold-down pins in my Glowforge but still had pieces that just wouldn't work.
You are always welcome to stop in anytime to hand-select your own boards.
Or you can order ahead for a scheduled pickup! Typically ready in 24 hours at your chosen store. Just call or order online. Available times are shown during checkout -- pick whatever works for you.