Why would you want that kind of ordered array?
Single walled tubes, without any strict QC, are ~400 per gram. That's three order of magnitudes difference.
So yes, he is wrong, and so are you (since we are talking about 'the cheapest I can find it').
Also, they aren't quoted in micrograms / nanograms. How do you propose they sell 1 microgram to someone who wants to buy 1 microgram? Even analytical scales top out at 1 milligram. The price for the copper substrate is 1EA - 1 each. The numbers you read as 30 micrograms is 30 um, which is micrometers, microns.