If cholov yisrael spoils more quickly, it’s because the stores are negligent in how they keep it. In Queens and the 5 Towns it’s not all that expensive — I can easily get it for $2.50 for a half gallon. I never have a problem with spoilage (unless my kids forget to put it back in the refrigerator). If your milk consumption is so low that you keep a bottle for 2 weeks or more, YMMV.
CY is pretty much only available where there is a concentrated frum population. If you’re traveling, that means BYOM.