Why not buy her a "bass max" upright pickup for $100 (fits in the wing of the bass side of the bridge)and a K&K ultra pure preamp about 100 bucks used. Both workhorses. Virtually indestructible. Ampeg Rocket B100, 1 x 15, cheap used, workhorse of an amp, no horn which can be nasty for upright bass bowing. She could play with Straycats on an off night with this set up.
P bass will never sound like an upright bass, I play both, my uprights are on the cheap end of the scale less than 5000, (the best upright I have ironically, I traded for an old p bass I bought for next to nothing)
P basses: I'm a p bass dude. I love them. I have a lot of them. 70's p bass are the best value of anything anywhere, ok some of you will disagree, but for the money and the resale value they are almost free to play. I bought an beat up 70's "s" serial for $500 here in Southern California (not stolen: I would never, ever buy stolen gear!) That bass sounds better, than way-more expensive basses that I own, and quite frankly the expensive ones are just vanity purchases (we all do it!) I could never get the money back out of them. So I never play the expensive ones just look at them and tell myself how lucky I am. When I play a good paying gig I take an old P bass. Everybody I play with is happy. This my opinion I am not trying to say I am right. Bass is obviously a passion for everyone here.
Sorry I am a terrible writer