Hello everyone,
I'm looking for a 4-wheel platform for an examination project ... (if possible I would like to spend less than 50-60 €) ...
ps: if you also have other nice platform to advise me, I accept gladly !! 
This is a platform I have used and like: JuniorRunt Rover Kit - RobotShop
There are others in this series and others like it on the same site.