Here is a link to a forum discussion thread on your subject.
Read all of the items in the thread, as there are warnings about what not to buy.
I am looking into buying the adaptable lenses (telephoto, wide angle, etc) for my Canon A80. I would like to know if there is a big difference between the Digital Optics, Opteka, Tiffen & Kodak aftermarket lenses that are available. Is there one that is better than the other, should I stay away from one particular brand or should I just splurge and buy the Canon brand lenses? All but the Canon lenses are on ebay for reasonable prices, but I am having trouble finding any kind of reviews for these products. Anyone with any experience and advise on these accessories would be greatly appreciated.