Its worth noting btw (and this applies for most 'e-crimes' whether it be shipping drug/steroid contraband, other illegal goods like counterfeit items, etc)
That most of these investigations do not start by the Police perusing some Internet forum looking to nab the source. You would think they do, due to the open nature of these forums, but most of the times it actually starts IRL specifically when something in the shipping protocol goes wrong. Eg postal inspector (for whatever reason) opens an item and finds contraband, or perhaps more likely, having an package intercepted at CBP then opening an investigation on the importer (which often includes contact local police, putting a track on the suspected party, etc).
In most scenarios they dont even follow up on the actual client sales to individual customers. Usually it just serves as evidence or as a way to force the defendants hand in accepting some shitty plea agreement where he forfeits all his proceeding to the local PD. I've always wondered how much $ these vendors make, but going off of recent busts Ive seen, it could be anywhere from 500k - a few mill that goes straight to PD forfeiture. Thats really the crux of most investigations, those are huge sums for any PD and investigations usually start / end with that in mind.
Side note, it says they began their investigation in July and the warrant was served in August. That's REALLY fast t/t, Colonial must have been pretty careless with whatever protocol he was following. Few mil in forfeiture proceedings for a month of work... doesn't get much better than that for LE