How are investment products such as derivatives priced?

To further add on to Gary's reply below, if you are interested to find out in depth, you can read up on the Black Scholes model (https://en.m.wikipedia.org/wiki/Black–Scholes_m...) to determine how are options priced. That said, I don't use it on a day to day basis when trading options.

Derivatives are priced based on the underlying assets.

Eg options are priced based on underlying assets and time value.
Long dated options are worth more than short dated options.