Tile Drainage

What sort of prices have you seen lately for tile and tile drainage installation?  

Here in 2012 we are around $0.60/ft installed for 4" regular perf and average project cost around $1,100/acre plus HST for systematic installation at 30' spacing, depending on the mains required and whether or not sock tile is necessary.

Was wondering how prices vary across the province, in all areas, but especially in eastern and northern Ontario.

Thanks.