Dubai to Riyadh is a short leg of about 460 nautical miles, well under two hours in anything with a jet engine, and one of the few routes where a light jet is a sensible choice. The aircraft is rarely the constraint on this route. The landing permit is.
Private jet charter from Dubai to Riyadh starts from $9,000 on the smallest suitable aircraft. That is an indicative starting price, not a quote: the figure for your trip depends on which aircraft are available, where they are positioned and the date you fly.