Catalytic Converter options and questions (2016 Mazda6)

[karthik0001]

2016 Mazda 6 on 98,000 miles.
I got the P0421 error code. Warm Up Catalyst Efficiency Below Threshold (Bank 1)
Mazda service charged me $150 to diagnose the engine and confirmed the O2 sensor is good and it's a Catalytic Converter that needs replacement.
$600- Labor
$1275 - Part

My local mechanic that I work with would charge me $250 as Labor but I'm looking for deals or options on Catalytic Converters.

https://www.carparts.com/details/Mazda/6/AP_Exhaust/Catalytic_Converter/2016/Touring/4_Cyl_2-dot-5L/APE641613.html

https://www.carparts.com/details/Mazda/6/Catco/Catalytic_Converter/2016/Touring/4_Cyl_2-dot-5L/CAT1517.html

https://www.autozone.com/emission-control-and-exhaust/catalytic-converter/p/magnaflow-oem-grade-federal-epa-compliant-manifold-catalytic-converter-22-123/1114606_0_0

I'm not sure why there is such a price difference. Any suggestion/ insight on part compatibility?