In the music world, Rode have a good reputation however their video range doesn't really seem to hit the mark. Their video microphones are the "NTG" range and it was said that it stood for "Not Too Good". However their latest video mic, the NTG3 does seem to be something special, but then it does cost £500.

You can pick-up xlr-minijack adapters for a few quid and the at897 will run off an AA battery, so you don't have to worry about providing phantom power.

It's really worth forking out for a decent mic as you'll be using it for years to come. The Videomic and the Sennheiser 300 are really limited to on-board camera microphones whereas you can deploy the at897 in a variety of ways. At the end of a long cable, or on a boom, for example. It's not the "absolute best" microphone but it is the best value for money in your £200 price range and certainly better than the videomic or 300.

Beyerdynamic also have a good reputation and their MCE 86 is supposed to be a decent microphone however I've never used one so I can't comment on it and it's a bit outside your price range.