I just looked up a regular one and they are 2-3 div?
If that's correct than a 6l would be 6d give or take 1?
If the stat rolls are bad it's a 5. If they are mid 6. And if the 90%+ perfect it's a 7+. Perfect rolls double the base price depending on difficulty to roll all perfect.(12d)
This might not be accurate but this is how i price EVERYTHING from d2 to this game.