Advice on simple eCommerce using Sites NOT the Zoho Commerce platform

Advice on simple eCommerce using Sites NOT the Zoho Commerce platform

I use PayPal Pro as my processor.

I am a Zoho One subscriber.

I have very simple eCommerce needs...I sell a few products which can be handled with PayPay buttons.

I collect registration fees for seminars.  This requires the registrant to select a date and number of attendees, (and name, address, email address etc.). If the number of attendees is >=2, then a discount is applied.

I don't see a way to handle discounting calculations in Forms, and I do not need the functionality of Zoho Commerce.

I'd appreciate any suggestions on how to address these needs.