Help getting value from a drop down field
I have a form where I am collecting information from prospective clients. One of the fields is "County" wherein I have listed all the counties that I provide services, and the cost for that county. When they choose their county from the drop down list, I would like a hidden field called "County_Cost" to automatically be populated with the correct amount. Even if they go back and choose a different county, that field should update. That way, when they're done entering all their information, and they click submit, a contract is sent to them with the correct total.
In my drop down list, I currently have each county listed like "Wake,46" and then another county is "Franklin,75" and so on. The number after the comma is obviously, the cost for that county.
Any help would be greatly appreciated. I'm not that good at Java and just don't have time this week to do the research.