You can get same functionality at a much lower cost, especially considering he doesn't need the packaging or enything else other than the transciever functionality.
I would go for 2.4GHz transciever (free frequency both in US and EU), a buzzer, a li-ion battery and an arduino nano (or equivalent), may be he wants to flash a led screen as well.
Sourcing from cheap China eBay sellers the entire solution would be lesser than $15 (not including the two Arduino: one to transmit and one to receive).