To be fair, 1,500 SAR is little, even if accommodation, transportation, food and documentations are provided, giving that you send most of that amount to your family back home.
You will want to do your own groceries once in a while and may not see your family for a whole year. So, it better be worth it. I am not recommending asking for more, as that is totally your business. I would like, however, to give you pieces of advice:
1- You want to save for your family. If finding a job is easy at this moment in your country, I would not expect you to resolve to driving in a foreign country, so money is important. Thus, see how much you need to send to your home-country and from there see if this salary suites you, or look for another job in your country or Saudi Arabia, BEFORE you arrive. Incidentally, Contractors of construction, petrochemical, and services companies get more money than this and only high school diploma is required, as Mega-Projects in Saudi Arabia made the government allow more workers to flow in. So, I recommend you look up alternatives.
2- If your food is supplied by the family, which is the case of my parent's driver, then that is going to save you plenty (somewhere between 350 SAR- 700 SAR). We leave the driver a portion of whatever we eat. Once in a while, I reaffirm, you may not like the dish and desire to buy something else from outside, count 10 SAR- 25 SAR per good meal from outside. So, I recommend you ask them if food will be provided by family.
3- Is accommodation shared or private? Usually, it is one bedroom with its bathroom and perhaps a little stove/microwave. I don't know how they manage to live in such a small area, as I am spoiled; I know I wouldn't last. If it is private, then this is way more convenient and safer to you, as you don't know the identity of other drivers/gatekeepers/guards, or who else comes in to visit. So, I recommend you ask them this question.
4- Is your sponser going to pay for Iqama/Driving license, Medical Expenses, Travel Expenses etc.? They could cost you plenty, as much as 400 SAR monthly for airplane tickets and 200 SAR for everything else. I say, 95% it is them who cover these expenses. So, I recommend you demand them afford these expenses so you don't have the strong motive to seek for other jobs.
5- You will want to entertain yourself once in a while. Rent a car perhaps, or use family car to go somewhere for yourself. Add the gasoline costs to the total. So, I recommend you put this in your mind.
6- Communication using cellphone is usually from your expenditures (unless if they frequently requested you call them and inquire, support or guide). Fortunately, it is not the case for the driver at my parent's house. They pay him an equivalent of 200 SAR monthly for phone calls, so he can call his family, my family, etc. It would costs you around this much. If you wanted Internet access, this could go around 350 SAR per month in total. I recommend you put that into account.
7- Something my dad noticed about the previous driver he sponsered years ago is that he used to go to neighbors houses and wash their cars. Even though this was unethical for him to do so, my dad did not make a fuss about it. Not everyone is tolerant. Put yourself in the sponsers' shoes, would you want the driver your paid lots for be not available when you need him? If you obey the law and bind yourself to the job you applied for and signed to, then you could avoid yourself and others the bothersome and headaches behind such ethical delimmas. So, I recommend you re-evaluating this idea.
In total, an average driver would spend anywhere from 300 SAR- 1,400 SAR per month, depending on the facilities provided. It is always your right to discuss your salary/benefits beforehand, as this will save your plenty of money and covenience. As to our driver, he tells me he spends 200 SAR- 300 SAR monthly for his personal expenses, clothings (cheap clothes I assume), beverages, etc.
Based on these expenses, 1,500 SAR may seem more than 2,000 SAR, if you consider the overall package.
To me, I am not in favor of hiring drivers, as this is amongst the treats of a lazy nation, no offense to Saudi's. Hopefully, with the upcoming transportational means, drivers would not be as necessary. I hope this did not offend you.
Regards,