New Shopper Group, also show default SG prices?

[EvanGR]

I created a special Shopper Group with discounted prices.
I want this new SG to be able to see the default prices also, so they can realize the offers they are getting.

I managed to get the original basePrice from the PHP array, but this is not enough because it's not affected by the custom fields.

So
1) How do I show the default prices (for default shopper group), in a way that they are also updated by the user selected custom fields?
2) Which VM script is responsible for updating the prices in the frontend, when the user selects a custom field?

Thanks!