Hymns of the Spirit was, for the longest time, available from the Unitarian Universalist Christian Fellowship for the princely sum of $5. But they’re all gone.
For a price, an online bookseller is probably your best bet (but not this one), unless you live near a church that doesn’t use them (or use many) and can spare one. That’s what this post is for. If you are looking for a copy or have some to spare, please leave a comment below.