(According to a survey by the Post Office UK adults have spent on average £158 on gifts for their closest friend in the last year. Around £62 is spent on Christmas presents and £47 on birthday gifts, which over a lifetime adds up to £6,800, and one in seven people will fork out more than £100 on a friend’s Christmas present.
When a best friend has children, the costs become even higher, adding an additional £53 annually.
The survey doesn't mention regifting. (Giving a present you've received to someone else. I always give people permission to do this.) )