What is the current price of milk payed to the producer (farmer) in the USA?

It does vary by location as well as quality. Here's a couple links that you should find helpful:

Hoard's always posts the latest mailbox price by location in every issue. http://www.hoards.com/mailbox

Every day this place posts the class 3 futures http://www.dailydairyreport.com/ Class 3 milk is what goes for cheese, it is typically the lowest value dairy product but when just under half of the nation's milk goes to cheese this is the main price driver.

Right now the milk prices are very good, however all of our input costs are way up too which offsets this a lot. With feed, fuel, fertilizer, and now iodine prices through the roof milk needs to be also in order for us to keep going.

Here's a month by month chart of milk prices over the past few years http://ycharts.com/indicators/milk_price/historica... This will give a good idea at how prices can change and you'll see that the spread between the recent highs and lows are almost double.

Small things that can affect our pay price include bonuses for components (having high fat and/or protein, as well as any bonuses or deductions for quality, which is based on Somatic Cell Count. Lower is better. Every cooperative or other buyer will have a slightly different scale for quality premiums. Here's the quality premiums for the Co-op we ship to http://www.mimilk.com/prem_progs.htm Chances are most others should be pretty close