what will you charge for a business plan of about 60-100 pages,
including financial and spreadsheets,  for an economic development
project based on real estate and tech company investments? What is
your experience?

Sorry, we don't do projects like that here.

This might be a better site to look for what you want:
http://www.guru.com/

From my personal experience, I assume that you want to show a
complete, detailed and bankable business plan from an importante
investment which may cover all technologic, economic and financial
aspects.

Only as a matter of information, such a study should cost no less than
50,000 Usd, but this number may go higher supposing there is clear
complexity.

This can get expensive, esp if this is your first effort at something
like this.  Even if you hire someone to help you... unless you have a
clear example of what you'd like and for what purpose, an effort like
this can grow into a high $ experiment.

A suggestion, if you have time on your hands, you can approach this in
stages.  Start hi-level... do some of the legwork yourself.  Start
with your strength... if it's just writing paragraphs about the idea,
start with that.  Then see what's missing.  Attend workshops, ask
others to peer review.  Invest in a $30 software that helps with the
basics.  Start with high-level #'s and work your way into details. 
Leave sections blank, but keep working on pieces that you feel
comfortable with.

Then you'll have an idea of how to use the professional help a little better.

If money and time is not an issue, here's how to find someone.  Find
out about local entreprenuerial groups.  Ask around, call up VC guys
and ask.  Call up an local MBA program to see what they say. 
Network... and talk to others who are doing similar things... it's a
good way to test your ideas and see how others are doing stuff like
this.

Hope this helps.