Add add-on services dependences based on sq ft

Add add-on services dependences based on sq ft. For example I choose 40 photos as a bundle and then choose CubiCasa floor plan as an add-on service. I want to be able to have floor plan price based on sq footage since it directly affects how much CubiCasa is going to charge me.

For example $75 for up to 4000 sq ft house and $150 for 4000+ etc.

Again that all for ADD_ON services. Don’t wanna implement questions to ask my client the SQ FT since he has already input that information