Finding a road bike for 5'2'' girlfriend Last year I bought myself a used (although almost never ridden) road bike from around 1985.  I love the bike.  It is reasonably light and I love the diamond geometry.  

My girlfriend wants to get a used road bike but we are having a hard time finding anything on Craigslist, Kijiji, etc.  I think that this is mostly because of her height.  She is about 5'2'' so I think that she would ride something like an 18'' (46 cm) frame.  

I have thought about looking at bikes with low top tubes or mixte but I think that they are heavier and more flexible than diamond shaped bikes.

So here is what I am looking for: 


A 18'' inch frame (give or take)
A diamond shaped frame (lighter, less flex)
Used ideally from the 80s or 90s so that the bike is under $300 for a reasonably well made bike.  (A newer bike would be great as well however I think that it would be out of the price range).  
Road frame with drop bars


Does this bike exist?  If so why can't I find any online?
I'm answering the unasked question: "How do I find a hard-to-find bike?" 

Certainly this bike exists, but you may have to stick with your search for some time before finding it. (I sympathize with the situation. I take a 19" frame in mens, and most bikes are too large for me.) 

Mens' bikes often have a reach that's a bit too long, and handlebars that's a bit too wide for ladies. (Not always, depends on your girlfriend's dimensions.) 

Some general thoughts: 


Work with your bike shop. They may have something in stock, but more importantly, a good shop will keep an ear to the ground for you. 
Try a bike co-op. You may find a used frame inexpensively, or even maybe a complete bike. 
Keep searching on Craigslist and Ebay. Learn what frames and bikes you're looking for; on Craigslist in particular, sellers often think that bikes only come in the sizes "kids", "boys" and "girls", and don't list the frame sizes. If you find out what bikes came in the sizes you want, you can at least target your searches better. 
Do you have a bike club? Spend time on bikeforums? Subscribe to any mailing lists for bikes? Spread the word! 
Did I mention to work with your bike shop? 


Stick with it. Keep searching. 

If you're not willing to wait, you'll have to either adjust your budget or your expectations. But don't lose hope; the right bike is out there somewhere.