My wife got into a no BPA phase, and since I agree that BPA is bad when ingested, and I love buying new gadgets I jumped with her and landed with both feet in the gadget aisle of the store.
One thing we found is a Mason Jar Straw Lid. This was awesome as the boy loves drinking out of a straw.
Actually, he mostly likes blowing bubbles in his milk through a straw. However, the lid keeps the bubbles in the jar.