Quality can be defined many ways. I have a quality green flourescent submersible light I bought from Academy for $20 and have had it for over a year without any issues. I use it a lot too. Academy - Optronics® NightBlaster® Fish-N-Lite Fluorescent Fishing Light
You can buy more expensive lights if you prefer but IMHO it is a waste of money.
I also have LED lights around the outside of my boat and they work as well if not better sometimes than the submersible light.