I would say it is a pretty decent offer..

And from what you've stated in your post about how you would like to go about spending. I would say you should easily be able to save
Qr 15,000/mo .

Umm usually most companies won't let you negotiate based on the fact that you don't have kids and hence it won't cost the company a thing.

Which company is it though ?? Most private companies are usually open for negotiations. You might be able to get that salary up by a couple of thousand riyals.. But then again it depends on how badly they need you.

But in the big Q companies like QP, Q-Tel, Q Chem, .... it is a little difficult to negotiate coz they've fixed salaries for each grade ..

Try negotiating for a higher amount, if they say no, then well .. this is still a pretty good offer.