Hi,
If you want to save a little money, the best is to park on the Disney Village side, near the RER station. Rates are much lower and you just need to walk 200 m to the entrance of the park.
Here are the rates (you can check them on vincipark.com site)
01h00 : 2,2
02h00 : 4,4
03h00 : 5,8
24 heures : 8
I live at 10 mn from the village and there is definitely no problem to park there.
Corinne
France