This is a good warning @Carmie . I wouldn't ever buy something like that from anywhere except Chewy or Pet Smart or my Vet. I don't buy things like that from Amazon, even if Amazon is the seller. I'm afraid they could be fake.
The Bluebird Carries The Sky On His Back" -Henry David Thoreau
Absolutely need to find out where your provider ordered their Seresto from. Some go through a third party to get a less expensive price. IF they ordered from a party OTHER than Directly from BEYER then neither they Nor you can be sure where the product came From. Can't hurt to ask.... Might hurt to NOT ask.
Are the $55.00 one from Walmart safe? I don't want anything from China for my pet and me if I can help it. They just don't have the same standards as the good ole USA. I know one of our dogs died in 2012 from those Chinese pet treats.