@mzs I have found also this one (seems exactly same) with much better pictures. But more detailed technical parameters are also missing (e.g. noise factor).
5 MHz - 6 GHz, 20 dB gain, max. 21 dBm … $9.56
http://www.ebay.com/itm/5MGHz-6GHz-Gain-20dB-DC5V-Ultra-Wideband-RF-Amplifier-/262491002656
What do you think? Maybe better options would be these two:
5 MHz - 4 GHz, 26 dB gain, max. 22 dBm, noise factor 1.1dB@1GHz … $15.48
1 MHz - 4 GHz, 20 dB gain, max. 20 dBm, noise factor 2dB@1.5GHz … $11.8
Which one would you choose? I like that second one goes down to 1 MHz, but first one has obviously better noise factor and gain. For TX on 868 MHz or 2.4 GHz and possibly also RX (on whole range).