I saw those in Lidle a few weeks ago for £3.99 and I bought one. They seem to be OK but I went for another type in the end. Depending on the position of the dish it migh be too small for an 80 cm dish.
Lidle had some real bargains then, 80 cm dishes for £14.99 I got one that is working very well, Double LNB for £5.99, I got one and works fine - Sat finder for £2.99, etc.
Salvador