In my humble opinion, it's not really about how saturated or not a sector is. It's more about what to sell which you can build up a rapport with your site visitors about.
So, if you know all about, say, cane furniture, you'll have a better idea about what to sell and how to answer queries about the products, rather than just comparing prices.
If you know nothing about the products, it's not life-threatening but you're starting at less of an advantage. You have to do more research among all those far too many manufacturers and items within that product range to choose which to narrow down to, and which suppliers of them to try out from all those thousands and thousands ready to take your money.
Also, from the supply side, it's far easier to know what to ask the wholesalers in order to satisfy yourself you are going to receive the genuine article, or a least an article, for you money.
Easier said than done? Only in that some will say no. But others will say yes and you get better prices, so it's worth the extra effort.
But look for other ways of getting supplies without having to hold stocks, too. They do exist and there are threads around here to give you ideas.