Why is the price for designing master template different from designing slides?
Basically, the two are different, as you can use a master template on your future presentations. It dictates the background, color, fonts, effects, placeholder sizes, and positioning. That means that next time when you open up PowerPoint and want to create a new presentation, those above mentioned things will be the same as your previous presentation - they will be the basic design for your next presentation. This will save your time and make your presentations to be more coherent. That is why designing a master template is more expensive than designing slides.