Wishing For Abilities.
I'm not far enough into 3e to really make the call, but wouldn't it be far easier and safer to wish for a magic item that gave your PC the desired ability (as long as they wore it)? I mean, isn't a ring of regeneration a better idea? Or do you fear losing the ring? You could just as well lose a permanent ability through high level dispel magics or death or some such, and all that cost will eventually die with you, but a ring goes on (unless destroyed, naturally), perhaps even being a family heirloom or part of your PC's family wealth. You don't want to toss it all away when you die, do you?
For my own tastes, I often use economics to help decide such things, if the world's economics are well considered. So if there is some sort of way to buy a Wish for X GP, you can virtually wish for anything you could buy that cost X GP or less, or Wish for anything that duplicated a lesser or equal spell.
To make a normally ephemeral spell effect permanent, however, you'd have to include permanency as part of the spell. That is now 5th level. Under the idea combining two spells and adding one is about right, 5+N+1<=9, so you could make permanent any spell of N =3rd level or less using that technique with just a Wish. Higher level spells are perhaps possible using an actual Permanency spell as well, but since that spell outlines which spells work already, there is good reason to believe spells not on that short list have extra problems.
No general rule will be able to take the place of the DM's insight into game balance, however, so some spells will simply be ruled impossible to have as permanent abilities no matter what their cost or level may suggest.
But I'd still just wish for the appropriate magic item if I were you.
Jim
