I appreciate that there is probably no all-inclusive answer to my question, but very roughly, is it better to sell materials (ores and plants) in single units or larger packets? For instance, what would a good quantity to offer of 1) iron ore; 2) jute; and 3) nirn root?
There are many people that could probably answer better than I (Foo really popped into my head when reading this) but when buying I prefer larger quantities, for ore/cloth/wood I would go for a full stack (200) or maybe smaller increments of a stack (50,100).
For things like resins I would ideally like to purchase the amount I would need if I were using it to upgrade an item, an example being Dreugh Wax- you will usually see these sold in stacks of 8 because it takes 8 to upgrade one piece of armor
For alchemy items (like the Nirnroot you mention) I would say small stacks are nice? Maybe 25-50 each stack. Personally when I buy these again I usually skip all the way to the larger quantities and buy full stacks when possible. This could be because I like to 'stock up' rather than go buy things as I need them.
Hope that helps a bit, or better yet if one of our more selling savvy members can reply with what they think is best ^^