Note: Please bear in mind that this is a left field idea that I have only put a little thought into. You may think of a good reason why this wouldn't work, or could have a negative impact. If so I'm all ears. This is simply an idea...

The Problem
The devs don't want an auction house, due to the way it can be exploited and how it affects the economy.
Players would like the opportunity to browse/buy items that other players have collected.

The Solution
Instead of a public auction house, how about a small change to vendors.
All vendors could have another tab of items for sale (perhaps we'll call it Traded), containing the last one hundred items that players have sold to that vendor.
A player approaches any vendor and sells their unwanted items at the vendors standard buy value. The items sold to that vendor (other than junk items) would then be listed on that vendors Traded tab.

Anyone approaching that vendor can browse his traded tab, to see what items he currently has 'Traded'. It's like a lucky dip, as the previous players might have sold materials, armor, weapons, or stacks of fishing bait. Checking back later with the same vendor would list different items that have been traded since your last visit.

This way, it keeps visiting vendors fresh, and all vendors would have their own list of traded goods, giving incentive to visit more than just one in a town while cleaning out your inventory.

There is no way to exploit it, as the pricing is fixed at existing vendor rates. The difference between buy and sell prices introduces another gold sink into the game, helping to slow inflation. Most of the items a vendor has Traded recently are likely to be around the same level of the zone they are in. Imagine them as local mini trading hubs.

At the same time, this grants players the ability to trade with the masses, and the chance at finding just the thing you were after, at one of the many vendors around town. Of course the down side for players, is that you are unable to control the prices, but this stops the exploitation of the system and you still have your guild auction houses where you can charge as much as you like.