Any one know how much will it cost to take a taxi to shaolin from Zhengzhou?

The temple is far from ZZ, so the taxi is not suggested.
From ZZ Central Bus Station (near the railway station), you can find the direct buses to reach Shaolin directly. The bus fare is 28RMB and the buses are operating from 06:30 to 11:40 and the interval is around 30 minutes.

Because there is 4 of us and we wanna go there direct if possible. any one know how much!?

Generally speaking, the taxi does not provide such kind of service.
If you want to take a taxi, it is suggested to hire a taxi in advance and the fare is around 300 to 400RMB.