Every touch screen consist of basically 3 main parts : screen, Digitizer(touch pad), Glass.
There are basically 2 technologies in screen production recently: LCD (liquid crystal display), Oled (organic light emitting diode ).
Lcd are more common, they are of TFT or IPS type. TFT are found in most low end china phones, Tecno, Infinix, itel, Realme and rest.This account for its cheap price and not too good display quality. This explains the fair prices charged on their screens repair.
OLED are are the latest technology in screens manufactured first by Samsung, they offer very rich color and faster speed.Super amoled are found in the Samsung edge series.These account for the high prices of most Samsung screens, they are exclusively sold by samsung.
Most of the cracks that happens to phone is usually the glass which cost between