It's always a good idea to change the water pump at the same time. The timing belt is a PITA on the Evo. Most shops will charge 5-6 hours for labor.

 

I did mine this past summer and I think the hours quoted from the shop were 3.8 for the timing belt, and 1 hour for the water pump. I paid ~$550 for install and a brand new mitsu water pump...which was the most expensive part. There were rebuilt ones for cheaper, but I figured I'd go OEM