these have definitely been discussed before, if not already made as a suggestion, but I will reiterate...
vendors should have
- some quick indication that the recipe is known (WITHOUT hovering over it)
- some quick indication that the recipe/item is already in your inventory
- some quick indication that the recipe is READY TO CRAFT (or at least, show it on hover over details)
these things could be indicated pretty easily, with small icons, color codes, something. it should be much easier to make decisions when you ave all that information readily available.
also, if this doesnt exist already, anything a vendor sells that you can't afford should be greyed out or partially transparent to indicate you cant afford it. not that you can't figure it out for yourself easily, but it seems like a no brainer enhancement to me.
if anything exists like this already, please let me know because I might be missing out, but its not covered in the vendor wiki article, so it should be documented if so.
BUMP for additional idea:
also a possibility: some way of viewing the recipes you "know" without standing at an alchemy machine. maybe just bind the recipe to the player when they learn it, instead of making it disappear. then you would just need to use the same coloring scheme to indicate which recipes you can trade and which you have learned (and were therefore bound to you)