If your price of £200 includes safety pads etc then I would suggest Pro-Jumps (which are same as PoweriZer / Fly Jumper) @ £135 inc delivery you would have money left to to get Knee, elbow pads & wrist pads from Pro-Jump and still a bit left towards a helmet.
If your budget of £200 is just for the stilts then your other option would be PoweriSer as the other brands are above your limit. We don't allow links to other dealers on this forum but if you search for it in google.co.uk you will find them
(Remember PoweriSer is not the same as poweriZer - the only way to see from the pictures is that poweriSer (with a S) has a beige colour footpad and poweriZer had a black one.)
As a beginner I would recommend going for the Pro-Jumps as they do everything you need them to do at a very good price but ask around and do your research