value in ancient computers like Commodore?

One of the biggest costs in business is opportunity cost, which is the difference in what you would have made if you had done something differently. There are two main schools of though for retail. The quick turnover and maximizing profit. Both can make you money, but here is my personal take on it.

The quick turnover relies on quantity of sales. To be successful with this method, you need to have a steady supply of product that is easy to turn, easy to ship, and requires little work/attention on your part once you have your system established. If you don't have these factors set, you end up having so spend much more time which cuts into your already slim margins.

Maximizing profit margins usually requires specializing. Finding a niche. Become the expert in your niche and have people coming to you. You get to set your price. They are paying for the product and your knowledge. With a higher margin, you can achieve the same income volume with far fewer sales or a much higher income with the same quantity of sales.

Or as the old saying goes, work smarter not harder.