I have been using the Cuisinart 6-quart model (this one: http://www.cuisinart.com/products/slo...) for almost 4 years now and am very happy with it. Four temperature settings (warm, simmer, low and high) and good programmability make it flexible enough for pretty much any recipe, and the size is great for cooking for a crowd or, more commonly, making big batches so that we have leftovers for lunch.
It retails for around $100 (available cheaper with a coupon), which seems like a fair deal to me since it's better built, has more options and is bigger than most of the cheaper models out there.
The problem isn't merely the supposed change in regulations (I have been unable to find a source document on this), but the fact that low-end slow cookers, whether old or new, do not have temperature regulation at all, save for possibly an over-temperature safety feature. "Low" and "high" settings mean merely low and high power, not low and high temperature. At the lower power setting, it will take longer to reach equilibrium temperature, but the final temperature will be about the same at either setting.
High-end units have temperature control units, so they can reach a safe temperature (above 140° F) quickly, without getting too hot. They also have timers.
I would avoid older units which heat more slowly. If regulations were changed, it was for reasons of safety.
Crockpots are great for certain things. I use ours regularly for making pulled pork - it couldn't be easier, and only wish that I had gotten one years before I finally did. They are also great for entertaining - for meatballs, side dishes, whatever. Easy to clean and convenient.
Ours is a simple Crockpot 6 quart cook and carry. Simple and reliable. None of those digital controls to get in my way. Please note that low and high will both reach 205-208 - slow just takes longer to get there. Warm gets to 180-181.
BUT ... if you want to control it at temps lower than that, then just get a simple $11 lamp dimmer from the depot. These are fully capable of handling the low amps, and then you can experiment with whatever temps you wish. I am in the early stages of using this, so that I can experiment with sous vide.
Yes..this will probably get moved but I am using Hamilton Beach Stay or Go slow cooker ( 6qt) and I am extremely happy with it. I had replaced my old Crock Pot brand with the new Crock Pot brand a couple of years ago but was never happy with it. The temp settings never seemed to be right and it seemed to cook things too quickly.
The Hamilton Beach model has been perfect.