These things are like gold on my realm. Something like 50gs for 1 on my realm, the downside is that you have a 5% of skinning and getting it and also it only comes off one type of mob.
So far i have collected 11 in about 2 hours so technically i have 550gs plus in 2 hours.
Uses of Cobra Scales are:
Cobrahide head piece(epic)-nice rogue, warrior or hunter gear,usually sells for 500-600gs.
Cobrahide back piece (epic)-again for hunters, warriors and rogues, quite frankly the best back piece i see to date, sells for 500-600gs.
Cobrahide leg armor-40AP and 10 agil.
It is to be noted that there may be more but those are the ones i can remember.
To all leather Workers out there, go grind for those Cobra Scales cause they are sooooooooooooooo worth the effort.