Please update your GTN UI.
1) Have a global search. If I want to see "Gloves of might Sith slaying", so I can set the price of the gloves I am selling, I should be able to do it in one search.
2) Have a check box for showing the search results price in Total price or Price Per unit. This is essential if your buying/selling crafting materials.
3) Have MORE options in the armor section. Light, medium, heavy armor. Then gloves, chest, legs, etc. All separate choices.
4) Separate the crew skill items by crew skill and then by type of item. If you are a Biochemist you really don't care about the other crafting items. So I would see Crew Skills==>Biochemistry==> Schematics / materials.
5) Be able to have all the drop down menus in a side panel visible at one time. Look at Windows explorer. Chick on a heading and it expands to show the sub headings. Click again and it hides them. How would you like to navigate through windows if you had to use the current drop down menu system?
6) When selling, have the game remember what you sold the single item for and multiply the price accordingly. Multiply by 5 when you sell a stack of 5 of that item, 6 when you sell 6, etc.
7) Have the vendor price listed in the item description. Not really for the GTN UI, helpful for selling.