And the same module here for $2.75 US (this price is typical of many vendors on Ebay) 5.50 Ea should be for a pair... Check it out.
[price-up] NRF24L01 2.4G Wireless Module, Genuine Chip – ElectroDragon.
I recently bought 6 of those devices and a USB Receiver "Dongle" for $9.95... "Free Shipping"... Too ? $22.00 Ea... Yeah I'll Bet... that they would love to sell a bunch at that price, oh yeah and the Features on the $22.50 board are built into the Chip. All of the nRF24XX series Ic's have those features... They're part of what drove the original design and that was an inexpensive Chipset that could co-exist with all the other ISM stuff as well as Microwave Ovens @ 2450 Mhz and most capable of 1000 watts or more @ ~ 2450 mhz as the ovens use a "Power Oscillator" (A Klystron of Magnetron tube) neither of which has any external frequency control (Oscillating Frequency is set by internal cavity dimensions primarily).
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