Hello, I am looking at seomoz keyword difficulty for some of my keywords. Almost all of them are between 40% and 50%. Someone told me that for this difficulty is very hard to rank. I want to know your opinion on this matter. The keywords i am evaluating are for amazon review sites and are something like best niche name (only for example : best men shaving or best cordless vacuum). Do i need to be scared by this measure of seomoz? In terms of costs, can someone, with more experience than me, provide an estimate in terms of seo costs to rank a keyword evaluated at 40% and 50% difficulty in seomoz ? Thanks in advance for your answers. Regards.