ive only had mine since november, infact ive only been window cleaning since then so i dont know about the rest of the year...
if you look here
http://localservices.ebay.co.uk/there doesnt seem to be many window cleaners adds on there, well no one near me anyway except me! i think people search on there and so i have linked the classified add to my website...
Last new customer from website was about 3 weeks ago