The Greasemonkey script Abef (A Better eBay Filter) has been updated with code revisions by Greasy Fork user kolalok for latest Greasemonkey compatibility and is available at the Grease Fork script repository.
Below is a write-up of the original Abef Greasemonkey script. Note that I am, preliminarily, working on a Chrome extension which provide similar features to the script, although no release date is available and it may not work out as planned.
A Better eBay Filter is a script designed for users of eBay. It filters eBay searches to hide item entries from sellers who have a feedback score or positive percentage below values you specify, or above for feedback score, or filter out Top-rated sellers. The input values can be dynamically changed to filter items into or out of view. Last values are saved between browsing sessions. Use A Better eBay Filter to winnow the display of auctions to sellers that match your preferences. The script has been tested on USA's ebay.com, Canada's ebay.ca, and UK's ebay.co.uk sites. It may work with other country sites, depending on whether they match the internals of the tested eBay sites.
NOTE: For this script to work properly, choose List View (not Gallery View), and turn on the Seller details option in Customize View, so that the seller information is displayed in the listings.
A Better eBay Filter requires seller feedback information to be displayed on each item entry so it can filter the results. After installing A Better eBay Filter, go to a listing or search screen. Click the View link at the top of the listings and choose Customize. This will navigate you to the Customize your search page. On that page, you should see a selection titled Seller Information. Check the box so that seller information is displayed in listing views. Note the exact wording may change depending on the site's native language.
After installation and setup, A Better eBay filter will display two status lines immediately below the basic Search line. The first status line shows the minimum feedback score and positive feedback percentage necessary to display an item entry. The initial values of 50 and 98.5 are forgiving, but easy to change. In addition, you may specify a maximum feedback score, or leave it blank if you do not wish a maximum: zero is not the same as blank. The default is blank (no maximum). In addition, there is a checkbox to filter out Top-rated Sellers. The second line displays an Update Filter button and the current number of items hidden from view by the filter.
You can change the score and percentage values to whatever you want. For example, if you do not want to hide new user auctions, you can change the feedback score to 1 (or 0) and see those auctions. Should you change a value, the filtered items message changes to a Values changed. message. This is an indication to press the Update Filter button to update the display with the new filter constraints. Each time you press Update Filter, the current values are stored for a future browser session or search/listing page display. You are not prohibited from choosing values which will hide all items, e.g. a Minimum positive feedback input of greater than 100 will filter out all entries, as will a minimum score higher than the maximum.