You can buy the rubber grommet from Der Franzose. 16 euros postage charge though so could be worth a try from Renault. There is so much slop in the gearchange mechanism that replacing them doesn't make a lot of difference - they are to ensure soft contact more than accuracy.
The springs are difficult to find second hand. But they are important to have for a nice gearchange. In the past I've used random springs. You can stretch them to reduce the tension.