Openning a hi fi shop

Come up with your own products. Sell to your local area and on line. Start searching for products you can put your own trademark on. Offer customers a service level they can’t get elsewhere, can’t get online. Offer upgrade materials. But don’t break peoples’ ass to buy it; make it attractive price-wise. I can think of many products and services.

If Agon had a "like" button, I would "like" what erik_squires and dweller said. Hence, ditto.

how to end up with a small fortune

start with a big fortune, open a hifi shop

I would not actually sell any gear. At least that would not be the major scope of my business. It would be some kind of high-end rental service or pawn shop inspired by sharing economy. I would offer short and longterm rentals and leasing. The client would pay reseller's price of the gear (let’s say 1000$). He would keep the device for a month. Then he gets back to my store with the machine and I give him back 900$. As an audiophile, I’m ready to pay 100$ to test in my system some expensive gear (before I buy it from the manufacturer or from the reseller). I would not care about esthetic aspect of that machine, I would not care how old it is, it may even have some issues. I’m ready to pay even more just to live for a month or so, with some piece of gear which othervise would not be my first choice.

First off, I would allow drunk people to rent out the showroom on weekends. I would also run a "hardware as a service" model where the customer doesn't actually own any of the gear but for a monthly subscription price they can swap out gear upon request. I do all installations and networking. Customers are charged for each service call. Different subscription tiers give you access to higher-end gear. Lowest tier is $100/mo., highest is $500. At the highest tier, for $6,000, you can enjoy a six-figure system in your house for an entire year, and then change it out next year if you want. You never have to pay for repairs and you're not tied into any piece of gear. You get to listen to everything hi-fi has to offer in your own home for as long as you want. Any gear I own that's more than 5 years old gets auctioned off. I would need about 50 customers at different service levels to make a decent living. But I'd be busy af.