Every Gloriads blog article tagged Bidding.

Amazon Sponsored Products cost only when someone clicks: from $0.02 per click and $1 a day in the US. How bids, budgets and Amazon's charges really work.

Amazon's bidding strategies: down only lowers your bid when a sale is unlikely, up and down can also raise it up to 100%, fixed keeps it. Which to choose.

No impressions on a Sponsored Products ad? The 7 usual causes: late data, a status, the lost Buy Box, an ineligible product, a low bid, narrow targeting.
Gloriads runs your Amazon Ads by rules you control, on all four ad types.