I'm sure there's already intentions to improve upon the current auction house as there's a lot of room for improvement, but here are some ideas I think are cool. I'm sure there's a lot more ideas too but this is all my small brain could think of at the time. If you have any suggestions to elaborate on top of mine please feel free to give criticism. I also made a few example designs as to what a more clean and easy to read auction house could look like.
Filters - A large part of searching an auction house and reducing the options to something you're looking for is this and there should be multiple filters for players to use, I'll list some examples of some good ones that I personally think would be a good fit for Pluto.
Rarity Search - Searching by the rarity of an item, I understand things liked "Crafted" prefixes exist and don't have a specific rarity, so probably a filter to search for guns with specific shards used as well.
Keep the current existing filters - Simplistic and work well
ID Search - Search for items with a specific ID range as some people enjoy collecting these items, E.X - search for items possibly listed on the auction with the ID 1-9999
Constellations Unlocked - Search if this weapon has constellations unlocked
Modifier Count - Search if a gun has max modifiers
Features - Functions within the auction house that players use to operate it.
Bidding on items - The ability to bid currency or any of your inventory items on items listed in the auction house. Players who listed the item can enable an option to accept bids or not.
Buyout Prices - Ability to set a "buyout price" using only currencies.
Removing Listings - The ability to take an item off the auction house or remove a bid you might've offered on an item.
Changing Prices While Listed - The ability to change the prices of your currently listed items
Notifications - Notifications to tell the player specific scenarios.
If their item has been sold
If their bid has been accepted
If their listing price has been updated or their item has been removed as a listing
If their bid has been denied.
Restrictions - Things to keep the auction house clean and tidy.
Larger Fees - Prevents auction house spam and allows for more serious listings
List Limit - Players can list X amount of items, will hopefully make players be more cautious with how much they list at the time and will keep the auction house tidy.
List Timings - Items can only be listed for so long after being put on the auction house, will allow players to see that their listed item might've been put up for too much by player standards and allow for item decay on the auction house so the same item hasn't been listed for months
Extras - Extra quality of life things.
Lister Name - See the lister of the item you're looking at.