A rule of thumb that I like to use for budgeting - find out what the
materials will cost (Home Depot or most any lumber yard is happy to
help). Then double the cost and add a little.
It is not an exact, but it gives a starting point. Once you've done
this, call around to a few of the local fencing companies and see if
they can give you a ballpark over the phone. Make sure that the
materials they are quoting are the same or close the same to the
specifications from Home Depot or the supply yard.
Note that there can be a big difference in the cost of the fencing
depending on the wire guage, coatings and post sizes.