I used Durabake a couple of months ago and was really impressed... It comes in a spray can and is really easy to apply and then you bake it for 30 min @350 degrees... I looked at the lauer link above and it comes in "pink lady"
...my girlfriend would pistol-whip me if I handed her a pink firearm.
If you get it powdercoated, keep in wind that it's MUCH thicker than paint, so it will have to be taped off thoroughly. Most powdercoaters probably wouldn't tape off things like the slide rails, which would be a major hassle upon reassembly.
Plus, if it's an inexpensive pistol as you said, it'd probably cost more than the pistol to get it pc'd.
Not trying to start a caliber debate or knock you in any way, but why not treat her to a new gun? You say it is a cheap gun? Why trust her life to a cheap .22? Yes cheap price does not always mean poor quality, and yes a .22 is better than nothing, but there are much better options out there and rimfire ammo itself can be less than perfect when it comes to reliability. Great for her though on carrying and choosing to defend herself! And if a pink gun will make her even happier than by all means go for it, but if possible why not get her something a little more reliable and more powerful? If not then I too would choose duracoat. Good luck with your decision.
Whatever pink firearm you get her just make sure you don't post pics of her holding it on this site!! Girls and guns threads seem to stir up all kinds of trouble on this site