Hi Danyela, this is the first site that I went to when I googled it but I can't tell you what it's like as I haven't tried it. you have to be careful of some of these sites though I would use a blind email address in case of spam just be careful that you check these type of downloads for viruses before you use them. It might be better to ask someone you trust whom has used a site.Sometimes the makers or the providers offer wallpapers but they have probably got their names all over them.
I hope this site helps though. All the best. Rab