Ask HN: Best route from developer to pentester

I have a lot of experience with web (rails, angular, ember, react), android and backend (nodejs, go), but got laid off a while back and am thinking of branching off a bit and look in to pentesting. It's an area I have always had an interest in, so now that I have time I wanted to delve a little deeper. There are some costly courses available, but seeing as I am getting short on money it is quite the risk without having some solid testimonials backing it up.

If anyone can offer me some advice on a good starting point I would greatly appreciate it.