I don't think any websites would be selling you cheap vbulletin licenses. Just visit active webmaster forums and you will find someone selling licenses. I see someone selling a license once every 2-3 days at Digital Point Forums. I've even seen sales of licenses at namepros forums. Another one you can try is admin fusion forums. These are all quite active and I am sure that if you make a thread looking for one, someone might be able to sell you because there might be many whose licenses are getting wasted and unable to sell.

If I were you, I'd just pay the full amount. It's better to buy it and not have to worry about possibly chargebacks. I talked to the vB marketing team and they told me ANYONE can make a chargeback at ANYTIME. Even after 2 yrs or later, which is why I say BUY YOUR OWN!! I now can get my licences brand new for $149

Thanks for the information. I didn't know about admin fusion. Would you tell me about its price on DP or any other webmaster forum? I have seen its price on adminfusion and someone asked a 110$ for it. Is it normal?

unless Jelsoft changed things recently, i am not sure this is true.  if it is an owned the license then I believe it is allowed to be sold once in its lifetime.  there are one or two other stipulations.  see the vBulletin site for all the details.

I'm not quite sure about that...
For one, I believe only the BUYER can make a chargeback, not the seller.
So chargebacks aren't really a problem if YOU are the one purchasing the license from someone else, its actually a good thing in case someone decides to scam you
And about being able to make chargebacks at ANYTIME - I think that buyers can only make a chargeback within 90 days of the purchase (Assuming PayPal was used).

Speaking of chargebacks, if you are using E-Gold, be sure that the person you are buying the license from has a high reputation and a respected member. This is because E-Gold doesn't support chargebacks and leaves the buyer and seller responsible for the transactions.