To clarify some posts :
Yes, they will bust you in a public place.
Yes, it is a felony. Any scheduled/controlled substance is a felony.
Yes, they normally go after the small fish to get the bigger fish; however in these cases the bigger fish is not some guy attainable to them. It's not your local pusher in the community, it's an out of area internet company that they can access without the small fish.
No, they most likely will not wait all week for you to show up. Unless...the Postal Inspector has an office in that building!!!