Too many variables to calculate. You would be best served to just get multiple quotes. Make sure you provide the suppliers the details and specifications so you are comparing apples to apples.
for example - Is this materials only? Will a pump be required? Will the forms already be in place? How accessible is the site? Will you have labor to help? Do you have a requirement for the strength of the mix? Will the supplier do any vibration or will you or your help or wont it be necessary?
Just some things to consider. I'm sure someone with more experience will add to the list.