They aren't usuall faked, but most of the bags you find at resellers, ebay, etc. are old and not particularly valuable/good.
From 2003 or later, the bags tend to be high quality and have very high retail prices. BUT, recently Ferre hasn't sold much in the USA, having closed the NYC boutique. Now, they only have a store on Rodeo Drive. So, there just aren't many here in the USA (most of Ferre's business is in Europe, esp. Italy)
Finally, before 2003, there were MANY licenses around the world slapping the Ferre name on all sorts of things, so there are many "authentic" ferre handbags that are total crap. Without seeing pictures, I can't tell you if your bag is real or not, but in general, 99% of the ones on Ebay are real, just old or from licensed diffusion lines.