price based on custom field

My client has a custom field called eb_Packages which is applied to the group booking form we have the number of registratns active but the client has the following details in it this is a radio list btw

Andy Warhol - $10000 (Table of 10)
Georgia O'Keefe - $6000 (Table of
Larry Rivers - $4500 (Table of 6)
Sam Gilliam - $3000 (Table of 4)
Individual - $350
Individual Patients & Artists - $175

now they want the total to be multiplied by the number registrants i no roughly where i need to change the code but how do i access the field values in the php code to do an if statement around that however they only want this to happen for

Individual Patients & Artists
Individual
so i need some way to access the Individual options

And to complete this feature, please ad a limitation to it as wel! This was you can create a event with multiple day options (with every day a different limit). Somthing like this:

Overall event: Swimming

Option 1: monday - 5 dollar - limit 50
Option 2: friday - 5 dollar - limit 45
Option 3: wednesday - 5 dollar - limit 39

Thanks a lot!