Tom,
While I don't have a a Badger 150 (I run an Eclipse SBS) I have had a similar problem in the past. You shouldn't have to hike your pressure up that high to actually get flow, and the problem is most likely a tip clog that is feeding air back into the color cup, or the interface between the needle and the tip is damaged somehow.
When the end of the tip cracked on my SBS (making the needle fit incorrectly) I would get the same problem. If the airbrush is brand new, this might be the problem. Check the needle and tip for correct fit, and if the tip looks cracked or stretched out at all, then it will need to be replaced. Try giving it a good strip down cleaning as well, and that may help.
In my experience, when paint is properly thinned, your working pressure should range from around 15-20 psi, with 25 being the max. Obviously, if you are spraying something extremely thick, then pressure will have to be increased.
Hope that helps!
Shaun