A few things to keep in mind:
1 - Most of the people who buy on here ARE NOT looking for the cards you are selling, but, at a CHEAP price, they will grab it to trade in the future. This is considered lowballing sometimes, but it is just simple reality.
2 - If you are ONLY looking to trade, then you need to have something that each other wants, which is VERY rare! Therefore you limit your options.
3 - It is a HOBBY, not a matter or life and death! I love the thrill of getting something for my PC, whether big or small. I have in the past been more excited over a $5 card than a $100 card that I needed!
I have sold PLENTY of cards in the past at well below their 'true value' because there wasn't anyone on here who wanted it. You can't expect there to always be a buyer for every card you sell. BUT, if someone sees a card for MUCH cheaper than normal, then they may choose to buy it, maybe even to flip it on eBay, but that is their choice. If you want full eBay price for a card..... SELL ON EBAY! haha
Good Luck AJ, just be patient mate!