The Amazon Buy Box algorithm takes into account multiple factors when determining which seller’s offer to prioritize, including:
Price, Availability of stock, Fulfillment method and seller performance.
Amazon Buy Box prioritizes the pricing the most, however, sales history and seller performance can have a bigger impact than it if you’re totally new to the market, you may not receive orders initially even with the lowest pricing, then stock availability, FBA/FBM, etc. as well.
Amazon’s buy box algorithm considers several factors:
Pricing your pricing must be Competitive
Stock Availability maintains your Stock Level
The fulfillment Method must be FBA
Account health must be good