Cost-Effective CPLD micropower 1.8V from regulated 3.3V
Having taught students for quite a while, and designed my own production boards, I think any saving in money will be lost with time and annoyance.

Zener's are a very variable component, think +-20% out of the factory. LEDs are not really designed for stable Vf so also can give you grief when someone changes their color for cosmetics or a cheaper part (people see LEDs as non-critical components).

A SOT linear like the MIC5377YC5-TR is dirt cheap, at $0.26 for singles from Mouser, 150mA and will have incredibly better stability with current draw, temperature, part variability, etc. vs. the LED or Zener, while being the same cost or cheaper.