Yes, more along those lines and even more so.. like "king size feather bed mattress toppers".. But good lord. That entire niche would be impossible to break into. Watch the ads as well. If you're seeing a ton of ads, yeah it means it's probably profitable, but it also often means it's hard to rank for. For that particular niche, if I was dead set at doing it, I'd probably think about alternate ways to get traffic to the site.. like a boat load of things like "how to clean a feather mattress topper" and hopefully have cleaning products that could be promoted. But even those ones didn't look all that easy.
So yeah.. If you're seeing results like that, it's probably a really good idea to stay away from that niche for now.
Keep in mind though that you're going to be doing product "reviews" as well. So you need to look for various products and check out the results for them to also get an idea of how you'll rank for them. I checked a couple out and I did see some affiliate sites on like page 3 etc. It's not important that the site ranks, it's important that you can get enough pages to rank.
Depending on your niche, look for other places to find potential search terms. For example, I was reading someones seo blog and he was doing headphones I think. He joined some applicable redits and came up with products that people were discussing and that were wide open in the rankings.