The low miles and 5-speed would help if you could find an enthusiast's home for it....outside that "best case scenario" from a buyer's point of view it's a manual BMW suv thats nearly 12 years old.
Have you looked around to see what others are going for? You may not be able to find something exactly the same, but you should be able to figure out a starting point/ballpark.
Used BMW X5 - in 58265 - Manual on Cars.com