A sous-vide or PID controller setup is the way to go if you don't mind dishing out a few bucks. I started out with the "stove-top/bain-marie in the sink" method and it worked just fine. It's just that the sous-vide method gives you a bit of set-it-and-forget-it moments, which is a welcome break, and fewer, if no, overshoots.
As for sous-vide/PID method, I would recommend any one of the 3 following setups:The "griddle" system
Fairly cheap yet very effective. Very versatile as you can switch from full pan to 2/3 pan to half pan if you want. A poster here sells these. You can find more info here:http://www.perfect-cheese.com/the-griddle-systemThe "food warmer" system
Any food warmer plugged into a PID controller. Very effective as well.The "Sous-vide Circulator" system
You have total absolute control of temperature as the circulator assures precise and even heating on the bottom as well as all sides of your vat. If you want 88F temperature, the circulator warms at 88F, other systems warm at 140F until 88F is reached. Is it necessary? no. This system is fairly expensive, but at least you can use the circulator for some great meals. This is the system I have, I'm a bit of a "modernist" in the kitchen so I didn't mind this extra expense. I would only recommend this setup for a "modernist" cook
. Otherwise, the other two systems are perfectly fine and are lot more affordable. Here's a pic of my 8-10L setup: