Depends on the power/availability of magic honestly.

Say in PF (1E) regenerate is a 7th level spell (for clerics) so you caster needs to be at least level 13. Cost of service for spells is: CL x SL x 10gp = 910gp
A trained hireling (scribe, mason, ...) costs 0.3 gp / day. So - even ignoring availability rules - it's reasonable to assume that cripples exist in the world. For NPCs.

Cause PF has a "wealth by level" stat which is a rough suggestion how rich (in magical items) characters should be. PCs at level 2 are already at 1000gp. There's no reason to not regrow your lost leg at that level.