Here is the site I use to figure up custom rates for just about anything that is asked of me. It is a custom rates guide for KS, but if you go down to the bottom of the page and click around, you should be able to find a simular guide for your state.
http://www.nass.usda.gov/Statistics_by_State/Kansas/Publications/Custom_Rates/index.asp
As you can see the rate guide stops at 2006 (they don't have a 2007 ready yet) I just add an additional percent for inflation, and a fuel surcharge.
For example:
The average custom rate for rotary mowing was $10.35 per acre or $63.16 per hour in 2006. In 2005,
charges were $9.58 per acre or $55.28 per hour. The average custom rate for tree shearing was $60.71
per hour for 2006.
I just take the increase between 2005 and 2006 and add that twice more for 2008. It does depend on the size of the equipment, and the horsepower range, etc.
I like using this guide, because it seems like the most fair way to charge out my work, I take the average of what is reported, and that's what I charge, when people want to know how I come up with my numbers, I have a published report to show them where I fall square in the middle. It really helps out my non farming neighbors to see how expensive it is to have a little work done. (sometimes they think just because it's sitting in the shed, we should be glad to go over to their place and do it for nothing)
(you can't afford to be giving away work, like cutting trails for free, not with the price of fuel and machinery nowdays)
