Lower level rewards like Powder of Fortification which currently goes for somewhere just north of 100k on Atlantic will go down, I guarantee it. The reason is because it's going to be hard to do a bod(any exceptional bod above 20 DC) and not get it as an option. The bribe system is still in play so any exceptional 20 iron armor or shield can also be made into PoF level in 1 bribe still... so any colored exceptional = a PoF.
They knew this would happen, tinkers can get a PoF keg that holds 250 charges now, or 25 PoF. Everyone needs the stuff but it's going to be very, very common. Copper runic hammers are also worth quite a bit because they are perhaps the best choice for making luck suits but the system will also generate a lot of those, the tipping point where things get a bit harder seems to be right around the bronze hammer level.
I personally do not plan on completing any large or normal bods at this point until I have a lifetime supply of PoF on hand, at a keg per suit a chest full of kegs should do

and since there is a month to go before this goes live I fully expect many of the multi-account 3k+ bods a day guys to have so much PoF level stuff stored up for release day that it really won't take long for the price to drop. Need PoF? Do a single bod, almost any bod especially if you bribe it once or twice... it's too easy.
As with any system there is a "most profitable" setup which varies depending on the market. My gut tells me that with the new system the "value" will be to either just turn in the ingots for cleanup pts directly(100 valorite = 1000 pts) or to use the stuff to make suits. I think some of the bod regulars are already making suits with their extra materials on Atlantic and they are about to have a lot of extra materials. Turning in ingots for cleanup pts to get dyes might not generate 5-8millon anymore if the new dyes are any good.
Cooking looks to be a disappointment on the rewards menu, there is a nice deco tree but not much else. Alchemy has dyes and tinkering has the 250 PoF keg as rewards and most of them give you tools to convert materials into better materials(at a loss of course, 3 for 1) and/or to find the materials you want guaranteed. The ore maps let you find various veins or ore but you have to get to specific co-ordinates which is a pain.
Overall I like the system but it's not likely going to be the cash cow it has become for the Luna elite with 10+ accounts. All rewards are easier to get now, no RNG involved. If you are sitting on a ton of bods right now you may as well turn in your iron still and your PoF bods but I'd hold onto any bod above PoF level, you'll have extra points for each of those if you wait.
re: Just turning in ingots for cleanup value... turning iron ingots into dull copper ingots is the only move which would increase the net value of what you have after a 3 for 1 trade, you'll lose net value with any other transmute so many of the rewards to upgrade mats are in fact not profitable. The maps on the other hand for guaranteed agapite/verite/valorite might be interesting.
Iron Ingot 0.10
Dull Copper Ingot 0.50
Shadow Iron Ingot 0.75
Copper Ingot 1
Bronze Ingot 1.50
Golden Ingot 2.50
Agapite Ingot 5
Verite Ingot 8.50
Valorite Ingot 10