Open access journals by definition are almost never free/minimal cost - the idea is the the author's are paying more of the costs associated with publication, not less. But in return, your article can be read or accessed by anyone.
If you want to fork over 5k, I would recommend PLOS ONE as a major, well recognized open access journal that takes the "publish anything with scientific merit" approach.
If you do not want to pay, Arxiv is your best bet. However, I will say that, while good papers end up on arxiv, so do lots and lots of bad ones (that's the point) and there's no concept of "peer review" there.
If you want to fork over 5k, I would recommend PLOS ONE as a major, well recognized open access journal that takes the "publish anything with scientific merit" approach.
If you do not want to pay, Arxiv is your best bet. However, I will say that, while good papers end up on arxiv, so do lots and lots of bad ones (that's the point) and there's no concept of "peer review" there.