The "$640" part made my eyes go wide, that's wild for one winter. Quick question though, how are you sealing the edges where the foam board meets the window frame? My first try leaked air around the sides and I basically got no savings at all. Did you use weatherstripping tape, or caulk, or something else? Also curious if you did one layer of wrap or doubled it up, since I've heard two layers with an air gap works way better but seems like a pain to build.