To this diagram could be added
Option 5: Buy direct from the publisher
Positives (+) Higher royalties for authors. Helps the publisher (who takes the) most risk in the venture, after the author Doesn’t feed into the evil practices of Amazon & the inevitable problem of censorship by Amazon of Christian perspectives.
Negatives (—) Doesn’t help bookshops on the High Street stay alive (Thanks to Ian from @matthiasmedia for these thoughts!)