Hi Tessseract, and welcome to SaleHoo,
Without overwhelming you even more with a stack of suggestions, let's just start at the start and see if we can work out where you are going wrong.
Now you say you are lowering your prices to try and sell stock, but you don't mention that you are lowering them to compete with others sellers. So the first question is how well do you know your competition?
That is the sellers in the same space that are selling the same thing or very close to it.
You don't just have to carefully research products, but you need to research the complete market, and that includes suppliers and other sellers.
When developing a business plan, there is a simple process that you should put in place, and it's called a SWOT analysis.
S - Your Strengths
W - Your Weaknesses
O - Your Identifiable Opportunities
T - Your Identifiable Threats
You should set aside 4 pages, one for each. You don't have to fill each page, but you do want to get as much as you can on each page. A detailed SWOT analysis means that you have researched your business model well, and it gives you a basic blue print to work from.
For example, clearly identifying your threats, such as competitors, means you can put processes in place that will increase your over all strengths, which in turn will reduce your weaknesses and may then increase your opportunities.
It's about understanding your business and to do that well, you have to understand your market. Making the jump from selling a few things for fun to developing it as a business model is no simple jump. Yes, getting any experience in online sales through any means is valuable, but you have to put solid core business principals in place to take it to the next level if you want to develop a long term successful business.