To date, almost all of the traffic to the site comes through the search engines, predominantly from Google and Bing. I have to say that I’m a bit reluctant to spend money on advertising. It’s so hit and miss. You can have all the traffic you want, but if they’re not interested in your product, they won’t buy.
But to answer the second part of your question – giving up a full time job in pursuit of financial independence through an online (or for that matter offline) business takes a lot of courage. For anyone wanting to take the plunge I would say: do your research first. Identify a niche you are comfortable with. Find a platform from which you can sell your product(s) – after a great deal of research I went with a free shopping cart called Storesprite, which serves my purpose extremely well. I would say give it at least a year before you make any decision to quit regular employment. It may even take five years to get to that stage. It really depends on a number of factors – how much effort you put into it, whether there is enough demand for the products (or services) you are offering and whether there is a vibrant market.
As to what I do better than Amazon – I don’t think I can do anything better than them. But I do try to match them. I think I have first rate customer service. I think I am open and transparent in my product descriptions – if a book has spinal lean and age spotting then I say so, if a record has a dozen clicks on Track Two then I say so. Some sellers try to get away with skimping over some of the facts regarding the products they sell. I couldn’t do that. Attention to detail and emphasis on customer service are two of the factors, I think, that have enabled the project to keep going for so long.