This depends on many factors:

• How much you earn.
• How many times do you eat out? and what type of restaurants.
• Does it include rent?
• Does it include a car loan? How expensive is the car?
• How much and what type of useless stuff do you want to buy?
• Gifts you buy?
• Vacations?
• ...etc.

It could be anything between QR2500 and QR100,000 (and maybe more)