Accepting An Academic Gift From Supervisor I have developed a good working relationship with my supervisor and I have expressed my interest in wanting to pursue a PhD in the field that I am working in for my masters degree. I have expressed interest in a textbook from another author in a complementary field that I would want to hold in my collection as a PhD student, and if things work out, as a professor. As well, I am my supervisors first student that they have had under direct supervision after their own PhD, as are they my first research supervisor. So there is a unique 2-way relationship as well for the sake of context. 

My supervisor has told me that she would be willing to purchase this book for me and I think that my supervisor would be doing this because they actually want me to have it for my future and in part as a gift to me. Personally speaking, I do not see any ethical concerns with this, but I suspect that I might not have a complete perspective on this type of exchange. Do you think that there are any ethical concerns that I should be cautious about?
There is no issue at all in such an offer. Thank them and accept the offer. This is an entirely appropriate sort of thing to do. Especially from an advisor to their first student. 

Gifts in the other direction have ethical considerations, of course. Gifts to supervisors can be misinterpreted. 

But, as you suggest, it is a gesture of support for your studies and your future. 

I would only suggest otherwise if the relationship had some sort of creepy element generally or you thought the supervisor had other than academic interests. You give no suggestion of that, so dismiss the idea, though it may be relevant to others. 

Hmmm. I'm reminded by this that I've done the same, though it was a copy of my own book.