Does she even want one?
Get her a disposable to see if she's even receptive to the idea first.
Here's one at LiteCig with a charger and carts for $9.99.
Not a bad idea. But is it really a disposable if it comes with a charger? The disposables I've seen were ones that sell in casinos and convenient stores, precharged, no way to recharge them or change cartridges. Just use them until they quit and throw them away. Seems like a waste.
This one you found seems almost like a mini starter kit. You can barely buy a charger or a single batter for that price usually. If it works well, that's a great find.