How do I Expand my Product Line Without Spending a Ton?

I built a website a couple months back to open up an additional sales channel for a product I sell on Amazon. I only carry that one product on the site.

Having a site has been a good way for me to start developing a brand via content marketing and my social profiles, but my conversion rate is awful, even with a good amount of traffic (had around 12k unique users last month to a post I wrote, but only had one person actually buy something on my site). Frankly I don't blame users; my site looks quite clean and professional, but I wouldn't shop on a site with only one product either. It comes off like a here-today, gone-tomorrow business.

Have any fellow warriors been in this position before? Any advice on how I can expand the number or products I carry without having to buy 100s of units of stuff I haven't validated yet?

I'm guessing most people buy very small numbers of a bunch of different stuff, see what sells, then double down on the products that do well and eventually sell the others off at cost to get rid of them. I'm thinking I could get very small quantities via manufacturer samples or AliExpress. Of course, the ultimate goal is to only carry my own private label products, but I'll have to work my way up to that point I assume since most manufactrers won't private label stuff in small quantities.

Any feedback welcomed.