It's worthwhile being clear about your needs before buying.
I bought a "wifi ferret" when they first came out. These wireless cameras screw onto standard electricians glass fibre rods for pushing and pulling cables. It has been invaluable for feeding between floor joists to figure out what electrical cables and pumbing run where. Lift one piece of flooring and feed it in. The ferret focusses from about 6" to infinity. So if there's enough light it can see at a distance. If you are really close, everything goes blurry.
Later I picked up one of those generic £50 endoscopes with a screen and 5m snake, 2nd hand.
This focusses very close which I sometimes need, but can't see further than about 6-12" and blurry at that. It's good to have, but the snake is awkward to handle and not as manageable as the electricians rods which come in metre sections, some flexible and some stiff. With these you have more control when you are trying to steer the camera around obstacles 3 or 4 metres away.
These gizmos all have LED lights in them but you can get better images by turning these off and shining a separate lamp if you have the access.
Here are some screen caps from the ferret. Looking in the floor with a lamp and checking the state of the cavity wall ties with the built in LED
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