Courier pricing tool for website

I need a script (javascript?) which I can add to a web site which will enable customers to obtain a instant online quote for the services I provide.
I intend to provide a number of services (probably about 5) ranging from economy to premium types. The front end for users would include the choice of service, type of goods (document, parcel etc), from, to (based on postcode, city name etc and using Google maps), additional drops (via), special requirements (text box).
The back end requires that I am able to set the rates for each indiviual service based on cost per mile/km, minimum charge, cost of additional stops, other one off charges (fuel surcharge etc) etc.
I need as much flexibility as possible. An example along the lines of what I want is at:
http://www.same-day-courier.co.uk/courier-pricing-map.php
THe left hand side would be the front end and the right hand info would be the back end which would not be visible to users.