Hey KikoLyne
I would suggest you some simple ways to get traffic for your website as following
Start with a list of all the blogs and forums that only deal in buying and selling of gold coins. Write very unique articles with over 300 words or hire a freelancer to write the articles for you. Post these articles on the forums and blogs on your list with links to your site.
Create a Facebook page, Google+ account, Twitter account and any other social media venue where you must interact with people whose interest is selling and buying gold coins from anywhere on earth.
Prepare to do a lot of hard work in these two areas and you will get a lot of organic traffic to your site which means better opportunities to get clients.