I would say that if she is liking nitro (did she specify what kind?), probably see about getting one used and buying a new engine.
You can find RC10GT rollers extremely cheap now, and they are tanks and RPM has them fully supported with hop ups.
If she is wanting something like a 1/8 scale, you will need to up your budget, but you can still find good vehicles online, even some reasonably priced new.
I just think 100 - 150 isn't much as far as getting a nitro, assuming at a minimum you are wanting one that is RTR and new.