I am separating your post to address what I think are separate concepts and worthy of separate answers.
1 - Individual/Corporate Products
2 - Product Saler Identification
There's not even a way to work out who you're buying from before you buy, which is something I think a lot of roleplayers would have at least minor concerns about - say I was doing guerilla warfare in Amarrian space. Even if I desperately needed a resupply, I certainly wouldn't want to buy any products off slavers or Amarrian loyalists, and likewise, they probably wouldn't be seen dead with a product if they knew Mixed Metaphor had made it.
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The market should let you see who you're purchasing from before you buy (or alternatively, for fulfilling open buy orders, who you're selling to).
I think this one is the easiest to implement since the data is already there. When someone post an order, it is tied to their name/wallet or to their corporation/wallet. Displaying the corporation and associated standings would be useful to a buyer. In addition, it would be nice for a seller to set a "fee rate" on selling to people based on standings.
I think this could add a lot to the market in terms of interaction and encourage trade-alliances to form as well as military alliances. Also, I do not see any big obstacles, no huge extra server load (an added calculation when you select your buyer alongside the 2 existing taxes), and it adds to the game.
Good idea! Maybe we should flesh it out and put it forward on the Eve Forums somewhere.
Actually, the problem with trading is more inherent to the extremely rigid way in which the market works, which introduces one extremely large difference from real world markets - lack of quality variance. A Megathron made by a newb with Production Efficiency I and Industry I will have much higher production cost and much longer build time than one I make, but both production runs will produce a functionally identical item. If he then chooses to sell this Megathron at a lower price than mine (almost undoubtedly making a loss, but hey, he's a newb), there's no logical reason for people not to buy his Megathron instead of mine, and rightly so - he's selling it for less money and they're getting precisely the same product. Every Megathron is created not only equal but identical. Any random Megathron on the market is functionally and literally indistinguishable from any other random Megathron on the market. There's no difference in colour scheme, component performance, material sourcing, manufacturing standards, ethical standards, testing standards.
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All of this represents a massive missed opportunity for the market in general. Call me unrealistic if you'd like, but what I'd really like to see is a system whereby a manufacturer can alter the manufacturing process of his ships so as to make them more unique - lowering production standards to produce units at low cost and higher speed, but of poorer quality, or raising them to produce more expensive, higher-quality units. Manufacturers would, for a relatively low price, also be able to brand their ships with their own colour schemes and logos, clearly distinguishing brands and corporations.
I think this is a little harder to implement and already exist a little, but with less definition/gradation.
I am going to take a "simple" example - the Merlin.
The Merlin has 4 variants with 2 different sets skills needed to build it (T1 & T2). A T1 manufacturer who wants to build a "better" Merlin, would build a Worm. Another way to build a "better" Merlin is to learn the skills needed to build the Hawk/Harpy. This is clearly not what is desired, since you would like to see more variety.
Perhaps Meta levels is the direction to go? (Ships don't have meta-levels, so that example breaks down)
Based on your skills and requiring more material as well?
Now, this is not as special as color schemes or logos on items (ships), but it does provide a manufacturer with some variety, building on the existing database. It seems like a way to "update" manufacturing a bit in a future expansion (which hopefully will focus on giving us more functionality on the industry/market side as a whole).
For ships, I am not as sure what could be done, short of providing a few implant/rig-like bonuses based on the manufacturers inputs and having them be fairly limited.
Thoughts?