Well, you said you were willing to spend up to $200 or so. That's good, because the whole set up won't be cheat whatever it is.
If you want to get "better than what she has" you'd have to find out what she has first. And it'll probably be pretty expensive to upgrade a full set of painting supplies from there.
As an artist, it has taken me years to build up my collection of paints, brushes, canvases, etc. because buying them all at once would be out of the question. If you're just buying the supplies for one painting, it might not be so bad, though.
Me, personally, I use little tiny canvases (4 x 6 inches and smaller) and those are pretty cheap. Were you thinking of getting one of those huge stand-to-paint-on-it canvases or something kinda smaller?
Find out what she does and what area of painting she does and it'll be easier to help.
As for the springing this on an artist thing...if someone did this to me, they probably wouldn't get a painting so much as a self-deprecating laugh and a shrug off. But I'd appreciate the new art supplies.