The basis of all eBay auction is the total selling price of an item, which is the price your buyer is willing to pay after all costs are totaled. That selling price is governed by this basic equation:
Fee + Shipping + Bid = Street Value
The fee is how much you pay eBay to list the item, commission, and PayPal fees. Shipping is how much it takes to get the item to the customer. The bid is how much the customer is offering. The street value is the sum of all costs and perceived values.
For all practical purposes, any item listen on eBay has the minimum street value of three dollars.
$1 fees + $1 shipping + $1 purchase = $3
That means this: if your eBay offering is not worth at least $3 to the buying party, the item will not sell.
Is a comic, or a lot of comics, worth enough to sell at auction? To answer that, you need to use the Completed Auctions feature of eBay. With this mechanism, you can see what sold and what did not sell, and for what price. From this information, you can develop your selling strategy.
Of special note here is the insertion fee. eBay charges this fee to list your auction. If an item does not sell, this is how much money you lose on an auction. If you are not attentive, the cumulative expenses of insertion fees can easily overwhelm your profits.
KNOW YOUR SHIPPING COSTS
Know your true cost of shipping, including packaging. An incorrect shipping price loses you money. This also means that you need to know how you will ship an item.
I recommend that you work out your packaging before you sell. You want to make a profit from your shipping, even if it is a small profit. You will need this profit to cover your inevitable mistakes in shipping.
Selling comics on eBay follow these basic strategies: single book, bundle, donate, gamble, punt.
Single Book - If you have a single book that fetches a nice price, sell it. If you have a neutral appraiser grade it, you can fetch more for the book. These appraisals cost money, so only pay that fee if you can recoup your investment through increased value. If you do not get a neutral appraiser, the buyer is depending on your reputation for the book's condition. They usually assume that you have oversold the book's good condition, so usually offer much less than book value.
Bundle - You can bundle books together into lots. This spreads the insertion and shipping fees across multiple books. This also allows collectors to pick up whole sets of limited series or sub-series. There are some series which will sell as lots, but not as individual books.
Donate - Some books have a clear history of no sales, even as bundles. To auction them is to lose money. If you donate these books to a charity, then you can take the donation as a tax write-off. You get to use the street value as the donation amount.
Gamble - Sometimes you can find no auction for the item that you have. It may or may not sell. Do you sell? That is your call.
Punt - Your time may be worth more than these books. Sell off the cream and recycle the rest. 99% of all comics have modest values, even old ones. Unless there is an active fan base for a work, the effective value of an item is nil. The Joker has a fanbase. Jojo the Dog-Face boy is just a curiosity. You can also use the other strategies below.
Selling or Trading to a Store - You could sell your comics to a store. This will make you pocket change. For those series that have value, like the Sandman, you can either sell complete runs (which the comic shop will mark up and sell as a run), or you trade them in for store credit (if you want more books).
Direct Sales - You can try to sell these things yourself where people see them. Without insertion fees or shipping charges, a $1 book is just $1 + tax.
Donate - If you donate your comic books, you can claim them as a tax write-off at STREET VALUE. You do not need to find a buyer. Consider this if you have lots of good sales. All that money that you have made selling your valuable books is taxable. Using your worthless books to offset those taxes is a fairly smart move.
Open Your Own On-Line Store - If you have enough comics, this can make you money. Of course, you have to open your own store to do this. You could also open a real storefront if you are inclined.
Put Up a Web Site - You can sell items off your own web site. The buyers find you via Google and you negotiate a purchase. This is not a secure as other methods, but can you can list items for free for an indefinite period of time. This helps you to match up some obscure comic (such as Captain Carrot) with fans of those obscure works. This method is very low-tech and very slow, but you can realize value there.
Note: Beware of anyone selling you a "super comic-selling system." The way that you learn to sell on eBay is to look at the methods and words that successful sellers use, and using them same methods.