How do low price toys implement RF communication
Most of the RF transceivers used in toys (and other wireless devices, like garage door openers and car locks), use proprietary protocols.  Because they are not using one of the standard protocols like Bluetooth or Zigbee, there are no royalties to pay so the RF transceivers can be cheaper.

Both the proprietary protocols and standard ones like Bluetooth and Zigbee use the unlicensed ISM (industrial/scientific/medical) bands. It is the licensing of the protocol that is the cost factor.

When you buy a module from SparkFun or another supplier, it is more likely to be using on of the standard protocols, and the licensing fee has been factored into the cost.