In my 5x5 keeper roto league, we have a max increase of $5 per player, per season.
In our winter meetings before the first season, we set limits on every statistical category with minimum numbers in non-counting stats like BA and ERA/WHIP. I think in four years, we have agreed to change these arbitrary baselines only one time, and it was a very minimal change. Its not a truly traditional way of doing the increases, but it seems to work great in my experience.
2012 H2HWS West A champion