I always feel a bit cheap if I buy off personality flaws with exp. My Champions gaming group has a saying about Psychological Limitations: "This is your personality. You get points for it." If you buy off the limitations, what kind of personality does your character have left?

The answer is generally "Mine". :/ Of course, my characters are always going to have *my* flaws anyway, so it always seems a bit unfair to saddle them with *even more*.

...and then, if possible, have them not change anyway.

This is certainly very realistic! People inevitably change, but rarely in an organized fashion or necessarily for the better.