At the £800-900 mark you have 2 main options as it stands. H&Rs or spax, the Bilsteins I suspect will be a bit more when fully launched.
There is others (GAZ comes to mind but they seem to get bad reviews on the clios) but the above seem to be the main/best options.
H&Rs are fixed rate dampers which is good if you like them as they are out of the box (expert set them up, nothing to mess about with etc) not so good if you want to adjust. From what I've seen (been in a couple of clios that use them), they are a very good fast road setup but maybe a little bit soft for all out track use (better than stock but compared to say ASTs).
I haven't seen a Bilstein kit that doesn't work well yet, so that's promissing(since not out for it yet). If the normal setup (B14) is anything to go by, they should be very good, and serve well as fast road/track day setup.
The Spax setup has got adjustable dampers (advantage if you want to play with). Not many reviews of them about yet. They are aimed as fast road/track day setup, and judjing by their spring rates they should be a bit firmer that the H&Rs but, not sure.
I've taken a punt with the Spax setup, based on availability and price. Will be using them day to day as well as on track.
I suggest that unless you're after some straight away, you wait for more reviews on the Spax/Bilsteins and then make your choice based on what you think it's best for you. Any of the above will be an improvement over the standard setup, but some will suit you more than others. If you can try to get in cars that use the setups that you're considering to make up your own mind.