Old poetry books

[AlRaven]

I hope I'm not going a bit "J R Hartley" here but for my sister's 60th we're looking to buy her an old poetry book. I've got two questions:

1) I know nothing abpout poetry or what she likes, so was thinking of an anthology of British poets of some sort.
2) Anywhere online that anyone could recomend for old/antique books? - I've been to Barter Books in Alnwick (which is a fantastic place)but they haven't really had anything suitable so far so I need to widen the net.

Any help appreciated.