Thanks for all your help guys - I have managed to get it working and I'm stuck on the last hurdle!
The last bit I am stuck on is getting the Guidelines part of the information to fill the price box - I basically need the "Price" value to display the text which I have linked to the branding dropdown (I have modified Thom's code to the "Page 7 Example 1" that I require. I believe I need to edit the SetPriceValue function that is following but i'm unsure as to how I change this to simply to display the associated text?
function SetPriceValue(){
if(!event.willCommit){
var nSelExp = 0;
if(!isNaN(event.changeEx))
nSelExp = event.changeEx
this.getField("Price").value = nSelExp;
}
}