So many products bought which don't work properly

I bought all of these products from the internet; I bought one after another because the previous one didn't work properly; this is so wrong. I'm scared to buy the next, because it might not work properly... I first experimented with UV photography using a tube-like blacklight, which worked. But then I wanted to have the same type of light, except that I wanted it to be portable; so I went for a UV flashlight; it seems to only give off purple light (pretty much). Next, I bought a Chanzon led which is supposed to peak at 365nm; unfortunately, the light is awash in visible light at the same time. Recently, I got a UV inspection light for inspecting fluid leaks in vehicles which is supposed to work well, and to my dismay, it doesn't give off as strong of a UV signature even as the Chanzon. I've just about had it with all of these products that don't work properly. I really wish that I had a way to measure the spectral output of my tubular blacklight, and get another one with the same specs. But the Nichia UV flashlight is only about 5 watts of power; that's like nothing, although the beam is supposed to go as far as 100 meters. So in the end, I just don't know; it's frustrating after you discover something new only to invest in it and it fails!