Placed in public, crowded locations, drawing attention with bright colours, bright lights and fun mechanical noises, providing reliable service to regular customers as well as attracting the interest of impulse buyers, vending machines are a great way of marketing a product, or at least they would be
if they weren't huge expensive cumbersome beasts that few can afford, and the intricacies of the leasing / financing / rent / refilling / maintenance deals are beyond the grasp of common folk (mostly because the details are so boring), who only expect to stick money in and get candy out of the thing, and the rest may well be magic for all they care.
In other words, vending machines are quick, simple and easy things from the customer's point of view, but complicated and expensive things from the sellers'. Why, then, not make selling from a vending machine as easy as buying from one?
The Sub-Let-O-Matic is a vending-machine-vending machine. Sort of. A mechanical, corporeal eBay.
For a daily fee (payable in coins), you get the use of one compartment of the vending machine. Stock it with whatever you're selling (making sure it's the right type of vending machine; you can't sell ice cream sandwiches from a Hello Kitty keychain dispenser), set a price tag, and let the machine take care of the rest. After your "lease" period is over, the machine stores unsold items in a separate compartment where you can reclaim them by entering a predetermined code. You can, of course, top up the machine with more coins if you wish to extend your lease of the compartment.
Additional options could include informing you of the stock status and other info via text messages, and you could set the minimum and maximum price tag for your product and have the machine work in "free market" mode, adjusting the price based on demand.
From the buyers' point of view, it's a regular vending machine. Insert coin, press button, receive product.
With some safety measures to prevent drug trafficking and/or food poisoning, and screening for illegal merchandise like bootleg CDs or such, the Sub-Let-O-Matic could become a good way for people to insinuate their product onto the market and under the noses of passerby on a (very) small scale. Perfect for various handicraft hobbyists, tinkerers, or maybe just someone who would like to get rid of three dozen porcelain puppies clogging up their shelves and maybe make a buck or two in the process.