As for how pros travel with it, they just have a hook up on the other side.
Seminar organiser, "super fan", local gym owner, Facebook bodybuilding friend...
And the pros don't have magical hook ups that are hidden from the rest of us. The same shit is available and very often at the same price. They often know who to ask for better products is all, eg sourcing orimiten from Romania rather than knock off useless Chinese stuff.
There's no benefit to being the (one of the) dealer(s) who supplied Ronnie when you can't really advertise it.