you can buy from Gulf carton factory - 4460 6635 - Industrial Area.
QPost is the best place to get it.
get the boxes from QPOST offices.. cheap and best
There are several companies here in Doha that manufacture carton boxes. You can get their details through Google. However, as Antony has suggested, supermarkets may also help you out and the cost will also be very low. I doubt if courier companies will help you out unless you want to avail their services.
Hypermarkets, Courier companies......
thanks guys for the replies.
I will check the Qpost and call Gulf carton factory .