Good burger buns are expensive and you don’t get many in a package.
Take two slices of firm deli-size whole grain bread, or French/Italian bread. Use a large biscuit cutter, wide rimmed glass or can, to cut out circles the size of the veggie burger. Lightly toast and use. Or, lightly toast the bread prior to cutting the circles. You don’t eat the extra bread and they’re cheaper. Or you can make the buns by cutting them out of fresh bread and using them without toasting them. It’s your preference. Don’t forget to save the rims in a freezer bag to use for future breadcrumbs/croutons.