Depends on the exit point. Hatta is no exit fee and 50 AED Oman visa fee + insurance for your car, maybe 80 AED for a week if not covered. I went through Al Ain once and the UAE charged me 35 AED to exit.yup, you got fees to pay but I dont recall the amount. And if your car insurance does not cover OMAN (most do) then you will need to buy insurance on the spot
We've once had problems entering Oman with an Ethiopian friend. They didn't grant her this tourist visa because of her nationality and job role on her UAE residency visa. Unfortunately there was no chance for her to get that visa, we've even tried to leave a deposit at the border. So best would be to see if you can find a list of nationalities who will get the visa on arrival.my understanding is that any resident of the UAE [and other GCC countries] may obtain a tourist visa upon entry to Oman. i do not believe there are any fees either. i am sure someone else can chime in with a more definitive answer.