widget like Gift Registry to limit registration but also has price listed and totals.

For multiple class registration choices that have costs associated. Need to have costs totaled for payment at end of form for payment.

You may try the Inventory widget: https://widgets.jotform.com/widget/inventory 

Here is how to setup the calculation: https://www.jotform.com/help/259-How-to-Perform-Form-Calculation-Using-a-Widget 

You can finally pass the total to your payment field: https://www.jotform.com/help/275-How-to-Pass-a-Calculation-to-a-Payment-Field