CiviCRM Community Forums (archive)

I'm wondering if anyone has any ideas as to how I can use the value of a profile field to influence the value in a price set field on the registration page for an event.

I have an event with online registration.  
And there are two examples where I would like to use field data to preselect price set options:

a) I would like the profile field "birthday" to influence an age-bracket based price (tot, child, adult) in a price set.  
b) If someone selects that they would like to take the chartered bus to our event within the profile, I would like the price set to reflect this automatically. For this example, I want to have the transportation options as profile fields in addition to price set fields so that our event administrators can make changes to transportation options for specific participants as required following initial registration. (I understand that price set participant data can't be changed administratively after a registration takes place as the price set data is transactional and represents payment at a point in time).
 
Any suggestions are greatly appreciated!

I'm thinking I could use some javascript to change the price set field based on profile field selection, but I'm a newbie to civi customization, and I'm trying to understand where I would hook that in.