I go through a lot of them too, but I always have more supplies coming in from other nurseries and labs. If you buy them in bulk, the costs should be fairly negligible in the grand scheme of things. If I were you, I would just factor in the cost of supplies when you're setting your prices next year. The farmer's market season is already well underway, so I wouldn't start adjusting prices on what you're already selling. However, if you put something new out, then go ahead and factor the cost of supplies in and bump up the price to reflect that.