So I wanted to start a marketplace where businesses like restaurants or cafes or bakeries can sell off unused or old machines/equipment they no longer use. Would it make sense to be so niche or should I just be a marketplace where businesses can sell whatever unused/old inventory they have? Like unsold clothes?
The specialty puts you above the gray masses of the generality - all things to everybody. I know MD who specializes in the intestines surgeries. That is all he does, and is booked for months ahead. Income $1.3MM. How about general and family set ups? Not much, comparing to this example. The same principal applies to other industries. Also, the same principal applies to the products form the church bells to the space rockets. New tech is too risky adventure, without very deep pockets support.
If this is the same person who asked the other question I just answered, this is still a poor idea. There's no money in it for you. Because of the high expense to move equipment, the secondary market is full of vultures who will wait for a bargain basement price. Depending on the specific equipment, you almost have to pay someone to take it away. When stores are no longer using equipment, it usually means they're going out-of-business, and the vultures know it, and wait until it's too late for the seller, just to get the cheapest price as a junk haul.
Sure, there are already some legitimate secondary market sellers, mostly auction houses and some warehouses. Warehouses spend a lot of time repairing used equipment to make it worth more than junk. Auction houses just move stuff at clearance prices and take a few percentage points for managing the sale on-site or in a storage facility.
Always go for the micro Niche as that goes a long way and subconsciously you would be able to support your business.. otherwise you would be totally dependent on others for your business and that's going