USPS says that the package was delivered, but I never got it!?

This exact thing just happened to me. I went to the post office and a similar event happened, and they told me to contact the seller. USPS just sucks. Try contacting the seller and see if they are willing to send you another one ( I did that and they gave me another one for free, except i had to pay for shipping, which would probably be a lot less than the $40 you spent)