Of course, the marketplace of clock sources is a bit of a rabbit hole on its own.
In addition to standard xtals, there are temperature-compensated or temperature-controlled variants (TXCO and OCXO), the latter reaching parts-per-billion accuracy (but also costing a lot). Then, there are ceramic resonators, made from the same material as piezoelectric transducers; this is cheaper than quartz and less bad than RC circuits - good enough for applications such as USB or Ethernet. Finally, there are integrated modules that might contain an amplifier and a programmable divider / PLL.
Of course, the marketplace of clock sources is a bit of a rabbit hole on its own.
In addition to standard xtals, there are temperature-compensated or temperature-controlled variants (TXCO and OCXO), the latter reaching parts-per-billion accuracy (but also costing a lot). Then, there are ceramic resonators, made from the same material as piezoelectric transducers; this is cheaper than quartz and less bad than RC circuits - good enough for applications such as USB or Ethernet. Finally, there are integrated modules that might contain an amplifier and a programmable divider / PLL.