I still don't understand why anyone would ever waste their money on those 2D glasses. The only time I can see them being needed is if you go to watch a 3D movie with a group of friends but in that situation surely your friends would either just not invite you, or watch the 2D version instead. If 3D gave me a headache or eye strain I wouldn't be going to watch 3D films in the first place so what the hell?!
You can make two pairs of "2D Glasses" with two pairs of 3D glasses anyway so it seems stupid to go and buy some.