Hi Kenbiki
Here's a link to some nylon string guitars in the $100 to $200 dollar price range,
Musician's Friend - Search Results I quite like the Alvarez, if you've got a store near you it would be worth popping along and checking a few out, I see your point about the Martin you should be able to get a pretty decent guitar with your budget, my old classical which is looking a bit battered as it's been around a long time cost me $140 dollars years ago, it was my best guitar once, although it has a few knocks it still sounds as good as ever and it's 17 years old now.
Another option with that budget are Martin Travel guitars.
Musician's Friend - Search Results
Good luck with your search
Best wishes
Chris
You don't stop laughing when you grow old; you grow old when you stop laughing.