One of the great things about the internet is that there are a number of different places to try selling your stuff quickly. There are dealers everywhere. There's eBay, of course. Some try Craigslist. Many forums have places where you can buy/sell/trade your sports cards and memorabilia.
If you are looking for a free classified ad opportunity for some of your lesser-priced material, we found one of those too. US Free Ads is the site that comes up #1 on Google when you do a search for 'free classified ads' and the site has a lot of traffic judging by the number of items that have been posted in the various categories.
The basic service is free, but they also have very low cost paid advertising too that will allow you to post pictures of your items and more. There isn't a lot of competition right now either in the areas where trading cards, autographs, etc would best fit. Of course, you can sell all kinds of other things on there as well.
Click here to sign up.