I imagine this is a supplier (as in B2B, Amazon is negociating prices for buying bulk stock from them to sell on Amazon as Amazon), not a marketplace seller.
For marketplace sellers, yes that's the rough gist. There are however many more factors: seller rating, shipping speed, whether the fulfillment is done by Amazon, and a few hidden ones.
Source: Have built price optimization software for Amazon Marketplace sellers in the past
(No fan of Amazon here, just trying to understand what you're saying.)