Picture posting is enabled for all :)
You might notice penny-pinching is a bit of a theme for me.
If you want a cheap reliable heater with good thermostatic control for background heat then an aquarium heater is a good option - but it needs to be in a substantial amount of water that won't dry out between checks. A big cool box with a propagator on top instead of the lid will put the heat where you need it most (propagators this size with thermostats are very expensive). You should also consider LED lighting - to get the maximum effect at lowest cost you need a timer that only extends the ends of the day, though some studies suggest that having the light on in the middle of the night can convince the plants that time is passing twice as fast and they need to speed up (look it up. I'm not totally convinced, and it would annoy my neighbours).Cheers.PS. 5W (50W equivalent) GU10 spotlights are cheap and efficient, and can be mounted inside the propagator lid (through holes with the sockets outside) - you are trusting they are sealed but their main use is in kitchens... You might notice penny-pinching is a bit of a theme for me.