where can I get an 18 inch wood closet door for a linen closet?
Answers:
It might have to be special made so it will cost you more...or if you know someone who can cut it down to size (don't cut the doorknob side) it would be cheaper. Or have you considered using louver doors? You could use 2 louvers and have it open in the middle. I did that in my sunroom going into a small storage room. I also like the idea it get ventilation that way. Get some prices and decide.
Other answers:
www.homedepot.com
www.homedepot.com
lowes or home depot