The buyers are just as bad as the crafters, if not worse.

I +2ed a shield yesterday and listed it for 15mil thinking it would never sell for that price. Well, it sold like a hot cake. I put it up before I went to do my leves and it was gone when I got back.

If you don't want me to make 27mil profit on a black pearl ring with double materia then wait until the price drops to 500k or whatever you feel it's worth. It's how I do it. All my gear is NQ apart from +1 crafting tools and my bow simply because I don't see the value in paying that massive mark up. But I'll happily sell that gear for those prices to mugs who will pay it. In fact if I ever pop out a crab bow +3 it's going straight in the wards for some mug to pay 30-50mil for rather than on my archer.

Blame the buyer not the seller lol. You're wanting to give this materia inlaying power to the buyers but it's their own faults that the prices are so high by paying it. The buyers have more power than the crafters in this game, in my opinion. It's them who decide my prices, not me. I'll generally milk them for as much as they'll give me. It sounds harsh but that's business.