If you are the first owner of the car and the sensors have never been replaced, at that mileage I would replace all four.

The prices you listed are somewhat low for non-generic Bosch, and about right for generic Bosch.

If you want to get sensors with the connectors already attached, first get under the car and check the color of each connector. Depending on the car, all four connectors could be different. The replacements must have the correct colors.

Generic sensors are OK if you're sure you can splice the wires correctly, solder them, and heat-shrink insulation over them. Personally I prefer those with connectors already attached.