i've advertised with the same ad in 4 different local parish type publications. 2 have given poor results, 1 has brought in approx 6-10 good jobs a month and one is just going out at the moment.
they cost me £20/3500, £25/4500, £30/4500 and £20/10000
I think it just depends if there is a shortage of w/c in that area.
hope this helps, i'd just go for it, you'll soon know if it will do any good, and £39 isn't gonna break the bank. good luck