WTTCHMN said:
The tip I didn't see listed is "Cancel Prime". This is the only way to guarantee you won't be subject to any price increases.
If you need free shipping, purchase at least $25 worth of stuff at a time. If you need movies/shows to watch, there are other much better deals (Netflix/Hulu/Redbox).
Prime is really just a way to lock people in to overpaying for items. Ebay has better deals on almost everything, even with shipping costs factored in.
There are also brick-and-mortars like Target/Walmart that have prices competitive with Amazon, and that's without paying $120 per year for the privilege of shopping there.