I agree with linds it will cost to much money just to ride on taxi for 14 hours.
My tip would be, from Sharjah airport go to Sharjah Bus station from there you can travel to Dubai for 5AED or you can travel to the capital from 25 AED from Sharjah bus station.
The taxi from Sharjah airport to the bus station will cost you around 10AED.
Our you can also travel to different cities of the UAE. But most visitor just travel to Dubai or Abu Dhabi the capital.
I was in Sharjah & Dubai & Abu Dhabi in summer of 2009. From Sharjah to Dubai is around 45 mins & Sharjah to Abu Dhabi is 2 hours there and 2 hours back.
I wish you all best in your travels in UAE.
Last tip in Sharjah there is no alcohol allowed if you carry it or drink it you will go to jail
Alcohol is allowed only Emirates of Dubai & Emirates of Abu Dhabi. Mostly Alcohol in UAE are in 4 star & 5 star hotels.