I run a niche retail store and there are two sides to this.
Most of our business is selling low-price, entry-level products. There's a 80-20 distribution of people getting into the hobby versus people upgrading after a couple years. Consequently most of our floor space and inventory is devoted to high margin, quick turnover, entry-level products.
In my experience the floor space is less of an issue for high end products than the capital expenditure to bring in the inventory. On the consignment side we only take products aimed at the remaining 20%. These are specialty items we wouldn't have in regular stock. It's a win-win because we don't have to deploy capital to bring the product in-store, but we do have space to showcase some higher end used product.
Also, from the customer side, people ask at the higher end, don't they? Beyond a certain level, it's more of a search and a quest than just browsing. So you mainly have to show that you have connections for certain things. Why does this sound like drugs now?
I know this from a few friends who are deep into tabletop and boardgames, and they would regularly work with the one or two small stores around to get some special, expensive item (to help keep the shop afloat).