Almost to the point of unusable, and at present it even 'discourages' serious use.

1. You cannot filter from highest price of the same item to the lowest price.
2. You cannot fileter for items that are of equal value (or below) of the same item as it can be bought from a vendor.
3. You cannot tell how many items in a category are available.
4. Cannot filter items you cannot even afford.

So having defined a problem, I propose an elegant yet simple interface design solution.
1. For each category of items, once a 'search' is conducted, have a dropdown list.
2. In each dropdown list, show the range of prices being offered, as well as the 'street vendor' price
3. Items posted at more than 20% of the vendor's prices get kicked to the owner in 7 days if unbought. (Let them keep having to post it.)

The exchange is a feature I'd like to use, but just looking at it is a pain, and as much as I'm thankful to Cryptic for putting together this game and all the hard work, I feel almost a little insulted that they willingly put infront of me a 'spam' of overpriced starting equipment.

Klingons don't have an exchange.