They are about £4 to £5 from UK DS, but that includes batteries, or it always has in the past. I'll try and find a recent invoice in the next day or so and check for you. The US price may be different, of course.
WOW that is expencive No wonder they have been making sets without them lately I am sorry but I don't have any of these spare - just the old ones Damo
Are you thinking of the special edition recycling truck which came without the flashing orange lights? I think that was just a stop gap before a new recycling truck comes out. I bought the flashing orange light from UK DS and that was about half the price of the blue one but came without batteries, which probably explains the price difference. The price seems reasonable to me, after all, you are getting a quality piece of electronic equipment.
Yes, and the lorry from set 4084 - Mega Construction SetI suppose you are right about getting a quality piece of electronics Damo