Dexy5 mentioned books as a cheaper option for running related gifts, so I thought I'd start a thread and look forward to hearing others' suggestions.
I am currently looking forward to reading Jen Scotney's Running Through the Dark, The Rise and Fall of an Ultrarunner published by Vertebrate Press. (I have a tenuous personal connection)
I love Richard Askwith's writing and can recommend: Today We Die a Little!: The Inimitable Emil Zátopek, the Greatest Olympic Runner of All Time [great for those of us of a certain age who remember him, but fascinating for all kinds of reasons], and a more personal Running Free
Boff Whalley's Run Wild
And a shout out to Sara Paretsky's VI Warshawski crime novels. Not read one for years but something about her detective's regular 3 mile runs sowed that 5K seed for me...