What are some good wide angle lenses for the Canon DSLR?

I have no idea real what they should cost but I went into a ritz camera store to ask about wide angle lenses. They told it would cost atleast $500 for just a basic wide angle lense.

I can't remember what brand it was or the dimensions.

I found one lense on ebay for $50 is it worth it?

titanium wide angle lense