Taxis can be expensive in Paris, does anyone know a reasonable and reliable airport taxi in Paris?

Too bad you didn't mention your destination! Assuming you're headed to downtown Paris, take the city center shuttle bus. It takes you in town and drops you off a location. From There you can use the metro/underground system. beware of lots of luggage! if this is your case, a taxi is the only solution. Ask the driver beforhand about how much it will cost you to get from point A-B. This will depend on taffic, but as one other answer person said, the fares are regulated and will be the same from one taxi to the next.

Where are you going, how many people are going with you, when do you need to be picked up, from which Paris International airport, and what does reasonable mean in euros?

extremely unlikely especially if you are not french

http://www.paris-airport-shuttle.com/ try that