Low voltage underground conduit – GreenBuildingAdvisor

I’m looking to trench in about 800′ of conduit for communication cables – phone, Internet, cable TV.  This be a straight run from the street, through farm field, to my house. 

Pricing out HDPE conduit – SDR 11 or 13.5 – is really salty at upwards of 85 cents a foot, and I may need to buy a minimum full spool of 5000′.

I started thinking about using irrigation/water poly pipe instead, which is far cheaper and more readily available.  I could easily place 2 runs of 1.25″ poly for much less. 

Is this a reasonable way to save money?  It’s low voltage, so I’m not worried about code or safety issues.  If it’s sturdy enough for domestic water supplies, shouldn’t it be OK for this?  What am I missing?