New or old number??
Depend on several factor such as:
1.)Number of alphabet in front,the lesser the alphabet the more expensive the number is
2.)Does the number hold a meaning to someone??
3.)Can the number form a pronounceable word??
Generally a generic  3 alphabet number 6 start from upper 20k range and the sky the limit(Priceless if w6 or p6 etc)
This is just a general rule or thumb
Sometime certain individual will pay a lot for a number which carries a meaning for him that is not relevant to you