I would take that video with the hugest pinch of salt if I were you. You have no idea what they might've done to the video in post. You need to try it out yourself 'in anger' before you spend a single penny.

If, for example, someone is giving a speech then you should mike them up with a decent lavalier mic. It will sound 'infinitely' better than something stuck to the recorder itself. Unless you want to them to hold it like a handheld mic (which is how products like the Nagra Ares-M are supposed to work). You should be able to get something like the M-Audio MicrotrackII and a half-decent lav like a Sennheiser ME-4 for less than £250 if you shop around.