Trader Joe's sells BPA free coconut milk but only in light. You could always just put it in the fridge til the cream hardens and drain the water out. Or drain out half the water and wind up with normal coconut milk.
Or you could buy shredded coconut and process it in a blender with water and make your own.
Honestly, I think the BPA thing is so incredibly overblown, at least with something like coconut milk. BPA could maybe, possibly, kind of be an issue when it's an acidic or heated product and a regular staple. Are you heating all your lunches in a microwave in plastic containers? That could be an issue over years. Do you eat canned tomatoes every day? That could be an issue as well over years. But coconut milk? IMO we're nitpicking too much, here. With all the toxins Americans dump into their bodies every single day and still live long lives in relatively good health, I think we're just becoming too obsessed with everything not 100% perfect as a community.
You could always just switch to regular milk. Milk is superior to coconut milk IMO
Don't put your trust in anyone on this forum, including me. You are the key to your own success.