As you are clearing customs, you have an enormous amount of choice near Paris! Grass field like St Cyr L'ecole is quite nice, you also get to see Versailles on the way in which is an added bonus..! I think landing was less than €10 and I think parking is probably around €10 per day.
Something which I read on the Parisian Airport documents (last time was last year sometime) is that they do not charge if you park on the grass at most of the airfields managed by Parisian Airports. (Please double check if that is still the case but I know I definitely benefited from this in the past).
I personally pick airfields with good links into town, or ones with instrument approaches if the weather is a bit iffy! I liked Lognes. Fantastic views of Paris when joining the circuit!