Get the live version of Shine On You Crazy diamond, its orgasmic, the version on pulse is slightly better than the one off The Delecate Sound Of Thunder.

Also Keep Talking, High Hopes, Careful With That Axe Eugene, Learning To Fly, In The Flesh, Hey You.

In fact just get all you can, you can't really go wrong, I prefer the later stuff, from Wish You Where Here onwards really, but if you like the more trippy sound you'll want stuff of the earlier albums like Saucerful Of Secrets or The Piper At The Gates Of Dawn.