sorry jug but you're confused with the front suspension here, its a far different story on the rear.
Dave - no nothing exists, and for a simple reason - it ain't simple.
Now off the top of my head I think the best way to do this will be to replce the std hub set up with something more like the clio cups have, which if I remember right has 4 bolts fitting the stub axle to the trailing arm. I would adapt the whole clio cup carrier onto a new fitting on the tipo swing arm - could be bolted like the existing hub without any bearing, or re-weld an new machined section - I would favour the machined approach. Personally I would buy the renault sport part, so I can use their shims. The benefit would be leaving the OE spring and damper positioning the same and parallel top and bottom.
look at 08 clio or earlier - they seem to have very similar rear arms
http://www.worldseriesbyrenault.ch/rst-clio/docs/Reparaturhandbuch/4-Chassis-1.pdf (4.3 rear sus). Or older version
http://www.worldseriesbyrenault.ch/rst-clio/docs/Handbuch_Manuel_de_reparation_cli.pdf .
Now as for offering a kit, I would forget that, I see no way this can be easily achieved for joe public, certainly I think guessing a price is pointless at this stage. Look to get your car as required first.
Also remember this, if you run negative rear camber on a swing arm then the angle of toe will alter and steer the car depending on range of suspension travel. If a road car runs any significant rear negative -1 to -2.5 then it will experince some rear steer effects in bump and rebound, also excess toe in/out heave and pitch. So I would be careful, a race car runs near as solid on the rear compared to a the road car where angular changes due to wheel travel are very small, thus less significant.
cars that use the tipo platform and rear swing arms of the same style (width vary), tipo, coupe, old bravo, brava, marea, tempra, 155, 145, 146, dedra.
good luck.
