Just my opinion, but I think $6 might be a little high to make any profit. Consider all your expenses, including labor (even yours), storage and fuel. At .20 a pound, that's $7 each at the yard (you make $1 per battery), each penny is .34 movement (up or down) so if the price drops to .17, you will only get your $6 back. (Figures were rounded)
(edit) Are you getting marine batteries? My example was based on car & light truck batteries, so what you get would be different.
Bookmarks