The foam is regular Great Stuff foam that you can buy in the spray can at Lowe’s, Home Depot, Menard’s, Walmart, etc. Be aware that there are both 12 Oz. & 16 Oz. cans. On a per ounce basis, Home Depot has the best price in my area (St. Louis).
I don’t know about the batting but I don’t think it matters. Any old quilt batting will do. I bought some that has a pretty low pile (I didn’t want it too fluffy). I’m going to start this weekend so fingers crossed.