Thanks for catching my dumb error. And yes, you are entirely correct: the Koss PortaPros and Grados provide no noise isolation. When I reread the original question, I realized my mistake (after I'd posted, duh).
In any event, Audio Technica has several models of ear buds with active noise-reduction that you can switch on or off, and both are under $100 with quite smooth, neutral sound. I've been using a pair for some years. It's important to get proper fitting nipples that are sized for your ear canals.
I have not heard recent Etymotics, but the ones I reviewed some years ago were rather shy on low bass, plus they were not supplied with a range of adaptors for different-sized ear canals.