RF clock synchronization

Is is possible to synchronize devices clocks via RF (in lets say cheap way) with accuracy of less than a microsecond?

Could you describe your system in detail.

For instance, RF travels 1 ft/ns. So if all of your nodes know their location and the location of the master, this potentially can be corrected.

There will be at least 3 devices with a radius of 5 to 10 meters from the master. This gives you about 67ns of maximum travelling time. I need clock synchronization accurate to 250ns. The clock speed will be 2MHz but the difference in slopes between the devices' clocks should be maximum 250 ns. Is it possible to reach ?