Assuming you will use Narita airport, taxi to Warabi will cost you more than 20,000 JPY (daytime) or more than 30,000 JPY (midnight) even though most of all taxi in Japanase honest.
I recommend limousine bus to Tokyo. It will cost you less then 3,000 JPY and you will get Warabi by train from Tokyo with fee about 300 JPY.
Anyway, learn from these sites before coming Japan.
Japan Budget Travel Guide: Transportation
Transportation in Japan
Japan National Tourism Organization | Plan Your Trip | Transportation