That split is fixed before an offer goes in, not negotiated deal by deal once a specific buyer shows up, so the agent is paid the same whether the home costs slightly more or less within the range already agreed at listing.
This is different from a lawyer's fee, generally $800 to $1,500, which a buyer pays directly regardless of how commission is split, and from a home inspection, typically $400 to $600, which is also a separate, buyer-paid cost outside the commission structure entirely.
If a seller will not offer buyer-agent compensation, which is uncommon, a buyer and their agent can agree in writing to a different arrangement before making an offer. Get your hand-reviewed valuation from Joel Dyck.