Why you need extra retainers

[GenJoe]

Last stack on my server sold between 300-400 each. NQ and HQ have the same prices.

If they are selling for 4750 each on your server then yes it's trivial making money.

Then Steel ingot isn't one of the items that would work for your server, although if you're willing to put up a stack of hq at 1200 and sit on it for 2-3 weeks, you might be pleasantly surprised.
As for your latter comment, yes it IS indeed trivial making money, which is the point I'm making.
It may not work for all servers, but it does work for a good amount of them, and if the items I've posted aren't profitable, look around, there will be other items that are.

Even today I can still get something like a 4~6k profit off just buying a stack and reselling it, not like it sells slowly either. It's... Amazing...

Yes, those kinds of items also work wonderfully if you're willing to sell a variety of them.

For example, you can sell olive oil from beast tribes, vitriol, cloths from sylph vendors and mythril ingots even.. If you have a few spare retainers you can stock up with those mats, and just relist once every few days that's very easy money. I'm taking similar concepts just slapping an hq stamp on it, and it seems to double/triple its price.

Okay, so then what HQ materials will move?

Also, what sells better raw materials or crafted materials?

What will move depends heavily on your own server and also depends on if there's recently been a person who just leveled up that certain craft.
For example, if there's been somebody who just leveled BSM from 1-50 few days ago, you may see a bunch of ingots at cheap prices, then you'll find no room to compete. If you're willing to wait a week or so, you can just sit on it and see.

Usually the crafted mats will sell better than raw mats.. I tend to specialize in mid-grade refined mats that need a crafter's handiwork, but is not an actual final product and it does quite well. Not too many people specialize in these markets, the profit margin is small when you look at it in a profit per craft sense.. But when you can hq a low end item in ~9 steps (20-25 seconds) as opposed to a 2 star mat at ~25 steps (70-80 seconds) your time is well paid for.. It's just hard to find a buyer, which is why diversifying and having 10 retainers helps.