Glass door for my closet?

Question:I want to put a glass door on my closet but my dad says that it'd be hard to find one...I thought that a screen door might work but apparently he says those are a different size than the standard indoor door size is.I'm not willing to spend alot of money...I know they exist because my friend just put a glass door on her bathroom doorway I just can't seem to find them...and I'm not willing to spend a whole lot of money on this...no more than I would pay for any other door from Menards...
any suggestions on where to find one? how much it will cost?
btw: what are the standard door sizes for both closets and front house doors?
thanks a bunch!

Answers:
Try Home Depot! Go to the windows and doors (they call it "millwork") department. I don't know if it's a stock item or if you need to special order them, but what I saw was very cool looking. Good luck!