I am openning a shop. What equipment should I sell

I never really liked them, but a lot of people seem to think Bose speakers have good base.

First thought in my mind is, why are you asking us? We don't know your market. What is your competition selling?
Sell something different to avoid price wars.
What price range will your client base be willing to pay?
Don't sell to high-end or they will pass you by.
What products are represented in your are by good distributers? See if they will do some consignment to get a feel for what people will bite into. What are you trying to attract most? Analog, HT, Stereo, mid range, high-end?
I wanted to do this a few years back and realized that the market was too competitive and the industry is too unstable. But best wishes

I would only do this as a hobby, I don't think you can make a living with 2 channel. Curiously I get the sense that the market is becoming larger but at low price points. If you are going to take the plunge follow Theos advice and find a niche and also be prepared to be a specialist in HT. Whatever you do don't undercapitalize and be prepared to work really hard selling yourself.

Anything but Audio equipment.

A lot of the long established "2 channel" outfits, are now more into high end home theater and custom installation. That seems to be where the money is retail.

They all still sell 2 channel, but it takes up less floor space than before and/or if there is lots of space, the 2 channel is in the back of the store.