Being able to craft non-buyable commodities that sell for higher prices than their normal counterparts would be a nice feature. For example,
You combine High-Temperature Alloy and Super Alloy to create High Temperature Super Alloy that sells for 'x' amount of credits, where x is determined by location. For example, a Shipyard. Selling a stack of HTSA would be more profitable than selling a stack of Hi-Temp Alloy and a stack of Super Alloy separately.
This would encourage transports to transport materials to, say, a crafting barge who would create stacks of valuable commodities for its cronies to sell. The barge could also smelt ore brought in from miners and use those materials to craft the component materials.
This has the potential to completely change the dynamic of making money in-game to a more engaging and fun system. I am 100% certain that people would rather use this system than normal trading; however, the previous system would still be in place for people who didn't want to get in these kinds of crafting groups.