One Item Store actually solves a real problem that a lot of people have. I know nothing about web development, and spent days getting a "one item store" WooCommerce/Wordpress site set up a couple of years back. The performance is woeful and I've been hacked multiple times. Your sites are so snappy and I'm assuming secure-by-default as they're static.

On the other hand, though, your sites look more like Craigslist ads than actual eCommerce sites. The font choice is ugly, and the lack of things like logos, contact/about pages don't exactly fill the user with trust.

If you polished it up a bit, I think you could have a real winner on your hands.