Hi Elaine - it's even cheaper now! Took about 2 weeks to arrive - I haven't used mine yet, but it seems pretty well made - I had to cut the plastic sheathing (very carefully so as not to cut the wires ) to allow the positive and negative crocodile clips to reach the battery terminals.
Add the correct quantity of oxalic acid (as detailed on the container) to the cup of the vaporiser. Connect up to a 12V car battery and slip the cup of vaporiser into the centre of the hive through the entrance.
ebay.us
I'm really pleased with the one I've got. Might order another to have a spare and to let one cool down whilst I treat the other hive.
Philip