The Grey Net is area of the internet where a person can find the types of things or information that are not necessarily illegal to possess but are illegal to use, assemble, combine, or have in public. Things like illegally high powered laser pointers mislabeled to appear safe, a silencer for your gun that only needs a couple holes drilled to function, ED medications without a prescription, or a set of universal heavy equipment keys for 14.99. The Grey Net is simply the shady area of the internet, the dark web's somewhat more responsible brother.
"Wow! Is this what I think it is?"
"It sure is, I found it on The Grey net!"