I would say, you don't have a traffic problem. But what you have is a metrics problem.

Do you have any metrics associated with the flow of traffic.

1) Are you seeing what happens when you place banners on facebook?

2) What demos are clicking (if any) your banners.

3) Where are you losing people. Are you direct linking to your home page, or are you pairing a banner with a product page?

4) What is the title of the headline that you are using?

5) What is the copy of the product page that you are using after the FB advert?

6) Are you doing any sort of re-targeting? Do you make the checkout process easy or easier on revisits?

7) Are you capturing any data from people who are visiting?

8) Do you have any type of newsletter?

9) How do people know you have slashed prices, are you telling people why they should buy at your site?

So many things I could go on. Put it this way, I have sold other peoples t-shirts on facebook as an affiliate. It's not terribly difficult, but the devil is in the analytics.

1) Images

2) Headline

3) Copy

4) Call To Action

5) Devices / Useragents

6) Geo-location

7) Retargeting

8) Opt-in

9) Funnels.

All of these matter and if you get it done right, not only will you start making sales. You'll start to make a lot of sales!

Good luck!