Looking for the best WordPress plugin for site-wide translation.

I know about a bunch of plugins, but they're all paid. I am looking to translate my website to Spanish because I recently noticed a large amount of SEO traffic coming from countries like Mexico, Argentina and Colombia for my website. I was wondering how I can achieve this in the easiest way possible, while spending no money? I checked festingervault it seems they have a good selection of plugins.. but there's a 20$ a month sur-charge, which if that's my last option, its the cost of doing business but before commiting to that I was wondering if anyone knows any options for free / cracked?

I would recommend translatepress