This article is from the eBay FAQ, by William B. Shaw toppsoft@yahoo.com with numerous contributions by others.
The answer to this question greatly depends on the type of items you are
selling and the type of buyers you attract with your listings. The more
exclusive your item is, the less important these features become. Remember
that these features are designed to increase your exposure by making your
item more visible or prominent when a potential buyer is looking at lists of
auctions that they might be interested in.
Before you consider paying for extra features, you should first make sure
the best possible keywords are present in your auction listings and titles
and that you are in the best categories. Buyers find auctions two ways - by
browsing categories and by searching keywords. If your keywords are
inappropriate or misspelled, your item won't even make it onto the list and
those paid features are worthless. I recommend you fine-tune your listings
before you start paying for extra features.
If you don't use counters on your auctions, start right away. You don't have
any other way to measure the results.
The key to making effective use of features like bold, highlight, and the
various incarnations of "Featured" placement is to experiment and to pay
attention to what your competition is doing. Unless you can differenciate
your auction listing in some meaningful way, your customers won't notice
your auction buried on page two of a category with 120 featured auctions. If
you are relatively exclusive in your products, skip the extra features.
The only real exception is the Gallery. If you product is very visual in
nature, a clear gallery thumbnail can make a huge difference in your auction
results. Keep in mind the goal is to entice the buyer to click through to
your auction, so make sure the gallery image you select is eyecatching and
the title gives enough information to reinforce the image. With the other
features, bold is bold is bold (as an example). With the gallery, you can do
a lot for your auction by making sure your gallery pics are better than the
competition's.
Finally, experiment. Watch your click-throughs on your auctions and track
how many people view your auctions with the various features enabled. Be
sure to keep other variables (such as auction length and ending day/time)
consistent to ensure your numbers are as meaningful as possible. If you
aren't selling multiples of an item, compare your results to your
competition by searching closed auctions. See if your selling price is in
line with others that using different options. If the selling prices aren't
improved by using the optional features, drop them.
 
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