It can add up. You can't buy in bulk because you only need between 2 and 24 of each screw. You want to buy extras, although you're trying to keep the cost down.
My new bronze chainplate bolts were $ 4 each.
For the teak and mahogany trim, I went for the silicon bronze wood screws with slotted heads. I think it looks better. Pricey though.
Everything else was stainless phillips.
Jamestown Distributors had the largest selection