The site captchatrader pays 1$ for about 1500 captcha entries. Two captchas appears in a second.
Hence it takes some long time to earn a dollar. But you can work 2 hours daily for about a week to earn 1$. I recently completed my first cycle and got paid.
Reviews on www are showing pixprofit as legitimate site and is paying 1$ per 1000 captchas. I am still working on the site and yet to analyse the site. Some of the negative points is that i) There are no clear instructions on the site about entry of captchas. Hence user gets confused when entering captchas. ii) I have seen my rating falled to 9 from 4 just in 20 minutes. And I have observed that I have typed many simple captchas.
It takes some time to decide the credibility of the site.