On ebay there are a few ways to save money, and make more money.
Firstly, if you want to buy and sell, find poorly advertised listings in your field of knowledge and resell it.
With collectables, do not underestimate the power of the featured listing to get more people to look at your listing and get on the pulse. Anything worth over £100 is generally worth featuring.
List you item around the fee increments, ie. it is cheaper to sell an item at a starting price of 0.99p then £1. Never use reserves. They are over-rated and you will never get a just price for your item as it is such a turnoff to buyers. If anything start the item just under your minimum, or take a risk and save some money with a 99p listing.
Take advantage of the cheap subtitles on listings and it is worth doing a bit of research into html to get some pictures, links and colours into your listing. Although HTML can not be added to these reviews, you can follow the ebay help guide to adding html and use a website like photobox.com to host your photos. These can be shown free and with links on your listings and is a great way to practically learn HTML.
Just be thrifty- do whatever it takes to make more money on your listing, without making a loss. do some researc and find out what a difference the ebay features make. You can't go too far wrong.