I need a thermostat that meets the following criteria.

1) Works with a 5-ton A/C unit (no heat feature required)
2) Programmable for different times
3) Most importantly and difficult to find - the ability to allow
anyone with physical access to the unit to adjust the temperature
within a fixed range but not outside that range (i.e. only between 73
and 77 degrees F  but not allowed to go above or below).  Should be
able to program this range into the thermostat.
4) Digital display

I wonder if this might be useful 
http://www.thermostatshop.com/ctb4wire-series.shtml "Set limits in
heat and cool" At $75.50, this is not a bad price for a thermostat.

This is a free comment.

Crythias, 

I called and the answer is good.  I want to pay.  Though I think maybe
I need an invoice or something to do it.

Andy

You can't pay me. I'm a commenter (my username isn't
hyperlinked/blue). If you've found what you like, go ahead and cancel
the question.

OTOH, if you're desperate to pay me, my paypal email is ... :) :) :) 

I'm glad it seems to be what you want.

If your comment is about buying from thermostatshop, I think you
should be able to order online or by phone.

This is a free comment.

Well thanks.  But if you change you mind I'm happy to cough up the
$20.  The advice was well worth it.