It really depends on what you want to record. You need to keep in mind the source material, the desirable polar patterns, the sensitivity of the mic, the frequency response, weather it can use a windscreen or not, the maximum SPL, and the signal-to-noise ratio.
I'd say go with some type of condenser w/ switchable polar patterns (cardioid, super cardioid, omni-directional at least), preferably with a response of 20Hz-20kHz to cover every possible sound source, and a high signal-to-noise ratio, especially when recording outside. When looking for mics, try to find one that more or less has these features.
An all-around good AND cheap (£40-£50) microphone doesn't really exist. Generally, the more expensive mics are more "all around" then the cheaper "one-trick-pony" ones.
I think it really depends how quality of a microphone you are looking for.
Edit: Hey I was looking on that website you posted. This one seems promising, and its a stereo mic.
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