Set Gas Price from code?

I deployed an ERC-721 contract to an evm-fork blockchain however when I submit a transaction Metamask signing window defaults to a 0 gas price.

I have a gas minimum for acceptance into our tx pool so a gas price of 0 fails.

How do you set the gas price from code?

My hardhat.config.js looks like this:

mrtrTestnet: {
url: API_URL,
accounts: [0x${PRIVATE_KEY}],
// set gasPrice to 1 BRCK
gasPrice: 1000000000000000000,

Support agent was unable to help.

Still unsure how to change the default Metamask gas price when sending transactions on a custom network…