L.A.
The crib probably has vendor info on it, or the craigslist ad probably tells what brad/style it is. Ours had missing parts (very common for cribs being pulled out of storage) and we just googled crib part manufacturers. We described what kind of crib it was, what part was missing and they knew exactly what it was. We bought the part and it got shipped to us.
took less than 30 mins:
http://www.unique-baby-gear-ideas.com/baby-crib-parts.html
http://www.productsamerica.com/