I have an unused HE-106X receiver module which is surplus to my needs. You'll find libraries on the forum/ playground for the HomeEasy line, which overlaps several others, e.g. ByeBye. Nicely made. Screw terminal connection to power, outputs.
Complete with "instructions"... patchy, and Chinglish, but not entirely useless. I will send them with the unit. The instructions also specify 12v 800mA for the receiver.
433MHz. The unit seems to output via a relay, and NO and NC poles are available.
I am hoping you are in the UK, so posting isn't a hassle, but will consider others. Not heavy.
To encourage you to pay a bit more, I would accept a cheque payable to some US or UK charity to cover both the unit and the postage of it to you.
Intereseted? Suggest three "big" charities for me to chose between... hopefully in different fields!... and what the unit is worth to you on those terms?