Nearly all of these simulator flight controllers use a pair of variable resistors to detect the position of the joystick. The resistor value is digitised and passed to the computer to derive an appropriate response. Trim and throttle controls function in a similar manner. Momentary or latching switches are used for on/off type functions, gear up/down, lights, etc.
The quality of the resistors and the fineness of the digitisation is what costs money. Quality microswitches that have debounce components fitted are similarly expensive.
Given two joysticks of similar cost, the more basic looking one is probably fitted with higher quality internal components to justify the cost. The chrome plated joystick with multiple fire buttons and flashing lights everywhere is probably not going to be the best choice for accurate sim flying.
As other posters have pointed out, reading the on line reviews of users is probably the best guide to finding the joystick most suited to your needs. A hundred pounds (UK) for a decent joystick is not considered excessive by flight sim enthusiasts.