Cannot Affect Self

GURPS Psionic Powers page 55, special limitations for Telekinesis.
The pricing at -20% for this allows some extrapolation to be done to produce a "Can Only Affect Self" pricing for TK.
-20% is beyond the highest known level of Bane for Damage Resistance which is at best -15% for being unable to stop a Very Common class of things.
Being "more common" than "Very Common" should mean a smaller discount than -20% is given. Perhaps something like -10%.
That doesn't seem like a big reward for limiting the super-broad amount of things TK can effect.
But this would be on top of other stuff you would naturally take if you only wanted to affect yourself, like:
*Reduced Range
*Cannot Punch
Category:Limitations