I agree with GM and Ed, the 105 is a great, versatile and very user friendly airbrush, I use mine frequently.
Depending on your application, another one to consider is the Badger 100G gravity feed. Smaller in size and weight, I prefer it for smaller area jobs, and especially camo freehand work. The 100G is my most often used airbrush.
It's identical to your 150, other than having the gravity feed cup. All of the parts are interchangeable, you could make a 100G using your 150, by just buying the forward body of the 100G with gravity cup, then swapping the parts from your 150.
The forward body of the 100G should cost about $25-$30 from Badger's website, referenced above. I also highly recommend Don Wheeler's website, a wealth of information of all things related to airbrushes.
Good luck with choosing your next airbrush.
Patrick