Although chimera scales are magically powerful, they are extremely rare in modern wandcraft. This is not out of any concern for safety, as they are generally considered no more stubborn than hippogriff feathers, and are more stable than Erumpent hide. The fact of the matter is that there are more recorded basilisk slayings in the past fifty years than there are chimera slayings in all of recorded history. This one slaying occurred in Greece over two millenia ago, so what scales were harvested at that time have been degraded, broken, and dispersed. 
Today, they are only found as parts of heirloom cores, and even then, all such cores are a more common core (often dragon heartstring) with a tiny fragment of scale embedded. Chimera wands are most common in Greece and the Balkans, although as they were circulated through the Mediterranean and former Roman Empire they are found throughout Europe. These wands are prized for their raw power, although they are difficult to control.