No-one else has answered, so I'll give you my 2p.
From personal experience, yes they work.
This has had steady sales since day one, but I'd build it into a full site (and probably create a better product too) if I had time.
A one page (or mini) site will cripple your SEO potential. Unless you're selling a very simple product, one page can turn into a scroll-a-thon to get to the pay button, which will put off buyers looking to quickly sate their impulses and lose you sales.
These days I prefer to sell (and buy) from sites with multiple pages and a strong brand. You can always pad things out with keyword rich stuff like history, ideals, aims and goals.
Bottom line: If a company hasn't put that much time and thought into their site, it makes it look like they haven't put much time and thought into their products.
ory.
