Okay, I know this sounds a bit bizarre but charity shops are great. They may not have the cool, retro reputation that vintage shops have but they can offer just as much, if not more.
You will find charity shops all over the city and one of the best reasons to have a look (besides donating to a good cause) is because you get a great sense of history from the bits and bobs you find in the stores. Often, I feel like I am back in the 90s which is great nostalgia for many people.
You can also discover some great finds for a bargain! From SLR cameras, vinyls or even great board games, you could stumble upon just about anything. The quality of stuff really depends on your luck but I have noticed that different parts of the city have a different style within the shops. Shelter is run by local volunteers so you will always meet friendly faces there.
The key is persistence, it may take time to discover a good find but looking is half the fun! There are so many to choose from and it’s a great way to pass the time whilst also being kind to the environment (re-use & recycle is the way to go).