Well my friend had the same idea you did. He leveled to 92 prayer and well its pretty useless, because having soul split may be nice but piety is much more useful. Along with the fact that unless jagex can really hammer the bots in runescape the prices of ashes/bones will most likely remain where they are or end up decreasing further. I would hold back untill you can either get 95 prayer or Extremes/ovls. People tend to not realize but extremes are much more useful than turmoil.