Do you know what sorts of paints she uses? Like does she do oil , acrylic? The supplies will depend a lot based on that. And paint can get very expensive (obviously canvas can too). I don't know what the best art supply stores are by you but if you are going to get stuff from a place like Michaels, stalk the coupons and start picking up things on sale each week. I got two tabletop easels for a steal last year by doing that, nothing fancy.
I'm guessing TSQ
can help you out with specifics more than I can, since I just paint every now and then for fun. But one thing to consider is that you often can't force this sort of thing. I've been wanting to paint the past few weeks because I've finally got my own place and I think it would be a great outlet to deal with stuff going on in my personal life. But I just don't feel like painting. And I would hate it if someone put an easel and canvas in front of me and wanted me to paint. It would ruin everything about it for me.
So, I'm not trying to be negative nelly, just saying that you need to consider that she might feel the same way.
Oh, one thing I did last year was this painting "class" where they just show you how to reproduce a famous painting. I mean, you don't have to do just that, and I kind of went off the path rather quickly. But you could drink at the event, there wasn't pressure to be especially creative, they provided all the materials, and I had a good time with my friend. Look around and see if there's anything like that maybe?