marc51,
If it will be gravity fed then 4" corrugated polyethylene pipe would be your most economical option. It�s about $30 per 100� in my area.
If you have to pump the water then 4� PVC would be your best bet.
Have you considered one 6� pipe? You would get more carrying capacity with one 6� pipe than two 4� pipes.
You can get slip-in strainers in either size.
More details (distance, amount of water available, etc.) would be helpful.

Larry