Rotary encoders vs. price

[NWChen]

I'm having trouble reconciling what differentiates popular FRC rotary encoders, especially since their price varies so much. For example, based on DigiKey:

• AS5145B Quadrature Magnetic Encoder; $38; 0.0879deg resolution
• Grayhill 63R Quadrature Optical Encoder; $54-$75; 64PPR encoder more expensive than 256PPR encoder?
• TT 6120 Hall Effect (Absolute?) Encoder; $15; 0.088deg resolution
• CUI AMT203-V Absolute Encoder; $49; 0.2deg resolution

I know max RPM and mechanical life varies between each encoder, but what else accounts for each sensor's price difference/popularity?