Well, after one day, I have the following report on the $27.50 vape (Noble VP400):
1) It works fairly well (for the price). It takes quite a while to warm up, but I got good vapor and excellent results once it got there. I think it's well worth the price. The only "downside" was that the plastic in the cheap whip has a funny taste... I used the whip from the Extreme with better results.
2) The set button does NOT seem to work as suggested above. The vape remembers the last temperature set regardless of the "Set" button. Each time you press the "Set" button, a LED goes from steadily on to flashing and back. Other than changing the LED from flashing to not-flashing, I see no effect on the operation of the vape. One annoyance is that you can set a temperature via the "Up" and "Down" buttons, but I see no indication as the the actual temperature or even when it gets there.
This is obviously not my first pick in vapes, but it DOES work and is well worth the $27.50. If someone wanted to try a vape before sinking a lot of dough, this would probably give them a taste of what to expect. They just need to remember that a more expensive vape gives more control, requires less fiddling, and (probably) tastes better.
Wally