Ben should really add a disclaimer when he offers advice like this.
Some of us prefer never to do smuggling at all.
Getting 3000cr/tonne
legally and ethically isn't too difficult, though finding it just one-jump-away for a large trader ship might be challenging. All you need is a High-tech in boom state at one end, and a Service economy in boom state at the other. Buy Medical Diagnostic Equipment (it's listed as a "Technology" good, not "Medicines") for about 2100-2800 credits each. Fly to Service economy - the superpower capital systems are good in that they have multiple stations owned by multiple factions, one of which is likely to be in Boom at any one time - and sell the Medical Diagnostic Equipment for 5800-6400 credits apiece.
Only drawback is that it's a dead-head return leg, as Service economies only produce biowaste. This will hopefully change with 2.2 and the possibility of accepting passengers for the return trip.