I too have been looking for something similar.
I wondered about the units from Mainline, as they are a bit cheaper, but perhaps a bit more work involved.
https://www.ebay.co.uk/itm/Wifi-max-Aerial-3-5GHZ-transmitter-and-Receiver-PRICE-for-2-Bargain/252865647123?hash=item3adff79213:g:AdQAAOxyTyBSYROh

There is some info posted on BATC forum. (Topic is 3.4GHz gain solution perhaps?)