Costs are generally calculated on a per acre basis and I generally figure $40-60/acre just for pumping costs.

The development costs are getting to be insane.  A center pivot with corner system runs around $165,000 in todays market.  That's up from $100,000 ten years ago.  Figure another $100,000 for a well and pump if you need one.  Not many wells get drilled unless one collapses.  A new pump in an existing hole is anywhere from $15,000 to $30,000 depending on depth and the new stuff doesn't last as long.  I pulled one this summer that was new in 04 and will have another from the same timeframe done this fall.   There is a lot of deferred liability sitting underground!

Putting in electric can eat up another $25,000 or a power unit will cost $10,000 to $25,000 depending on fuel type. 

Repairs are minimal for the first 10 years or so and after that it's a crapshoot.  Tires, sprinklers, etc.  I put new tires on an 18 year old machine two years ago.  $600 each and did 14 of them.  Tires is a real cost anymore.  We haven't even talked about RE taxes yet!

Right now we are all concerned about aquifer water levels.  The bureaucrats have a goal of putting limitations on how much we can pump on an annual basis.  The aquifer levels fluctuate depending on snow and rain(local and in the mountains) and how much we pump.  Their trigger level is a 1978 level that we "shall never fall below."  In the past 15 years we've been close to it and then recovered to record or near record high water levels.  This past two years we've pumped a lot of water which is leading to a lot of concern.

So, worst case scenario?  IMO it's not the pumping cost.  It's the capital infrastructure required to raise a crop and the potential for the NRD to limit our ability to use it.