I took a sample photo with the filter. As you can see the focal range is very small, the middle of the 50p coin is in focus, whilst the Olympic logo and the bottom of the coin are out of focus.
Below is a test video I shot using the cheap macro filter with my EF-S 18-135mm lens on my Canon 600D HDSLR camera. As you can see, the results aren't bad, it does allow you to get closer to the subject, however there is a lot of distortion in the images. This is due to the filter being magnified by +8, I should have purchased a +2 to start off with. I think the shot of the watch came out nicely, and is a great example of how these cheap filters do actually work.
Is £3 still too much? Why not go to a micro-budget and actually use a magnifying glass, watch 'Knoptops' video on YouTube.