Most Helpful Guy
It kind of depends. If she had a great job and plenty of disposable income, and she could afford it with less than a month's disposable income or less, and she clearly wanted to buy it for me, I would be okay with it, and very appreciative.
If she had to really struggle and sacrifice to get it, especially if she put off important things to afford it, then I would be uncomfortable accepting it. I would make my appreciation VERY clear, but I would want her to return it and spend her money on the important things she needed, rather than on me.