Moms good deal?,hubby has no idea in Life of a Mama Cat

I bought 500 sealed unused milk bags for $5.30 at Goodwill. My husband says I am being wasteful and bringing junk home. Did I get ripped off? My baby is going to be breast fed but I am going to pump too. I thought it was a great deal.. according to walmart.com it's $22.97 a bag to purchase there. I bought 5 bags from Goodwill