While doing a quick toilet-paper and paper towel run at Costco the other day we spotted these very large Method hand wash refills. We've never seen refills this big outside of Costco, so have a feeling they're exclusive to the discount chain.
This photo is for scale - as you can see, it's really a rather large bottle, 96 oz to be exact. We can't find this size of refill anywhere online, including the Costco website, so you may have to go in person to catch this deal. Oh, did we mention it was only $6.99?