Alessandro,
You must not have looked very hard.
http://www.etrailer.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=E&Category_Code =ls Has them, and they are not expensive. about 30.00 bucks each side.
If you need help, I can look up the part number for you . It doesn't take much to jack up the trailer either. A floor jack on a piece of plywood should do. If you dont have one, Walmart sells them for under $50.00.
Sorry to be so condesending, but people here have been trying to help you. If you need a detailed description of exactly how to do the job, I am sure we can come up with that too. I would not take the fenders off. that is just added work.