In addition to Rayner's suggestions, there are
- parsimonious (avoiding excess)
- stingy (unwilling to spend moneyungenerous)
- miserly (inclined to hoard money)
- Spartan (characterized by self-denial)
Stingy and miserly are pejorative. Spartan might evince a degree of admiration. Parsimonious is purely technical, a neutral evaluation. A solution to a problem might be described as parsimonious, if it is the simplest possible answer.
There are many others.