Ebay is about timing, details, presentation, research, options, patience and a little luck. If your listing is the 10 dollar one I'm seeing, I can tell you a few things done wrong. First off, only offering to mail it, versus emailing it would have killed you chance immediately, as most buyers who are getting a digital game, want it NOW. I personally understand your policy on not emailing, as I used to do it that way as well, but your lowering your potential buying pool greatly.
Your other mistake would be listing it as "voucher" only in your title. If you search this item, you'll see almost everyone else also has "code" along with voucher in the title. So if a buyer does a search for "Final Fantasy X-2 code", your listing won't come up. This will also diminish views greatly. If you see others getting the results you want, do what they do(whatever that may be).
These things might not seem like much, but trust me, they can greatly effect your final outcome. Research is key, as you always need to see what similar items are going for, and what those listing may or may not offer. When you look and see other similar items selling for 20, and your's didn't sale at 10 after the first listing, then you have to ask why? Yes, sometimes the other listings could have been lucky, but more often than not, it's due to something their offering, that your not.
It's also good to watch the traffic that comes to your listing, there's counters for a reason. You also have to have patience. I can list items that take days, weeks and some times months to sale. Certain things do need to be sold quickly, to maximize profits, as some items value get lower the longer their available. This is especially true for most video games, but this is where research is key. If the average price is dropping, act accordingly. I hope this info helps in any future sales you may have.
