In summary : 
I am in need of a piece of an equipment that can maintain a stable
temperature of an enclosure at a variable setting.

In Detail: 
I am starting to brew my own sake (Japanese Rice Beer [not wine]).
There are absolutely no books or good websites on the whole process.
I've got all of the required ingridients, and am now in search of
equipment. In particular, I need something that will be able to hold
a container with my rice (brew) and maintain a steady temperature.

Very Important:
The temperature must be at 30°C (86° F) for 40 hours for the first
step of the brewing process, and at 15°C (57°F) for two weeks(!) for
the second step.

I am living in a one bedroom apartment in NJ, where the temperature is
usually (hopefully) around 70°F, and once the summer comes, it will
probably be much hotter, with the exception of the times when I'll
turn my AC on (I don't have central air conditioning), not to mention
much colder in the winter when I won't have heat during the day. So,
in other words, I can't use Room Temperature, or my household
thermostat to control the temperature of say, my kitchen, where the
sake is brewing.

So. The dillema... How to create a small enclosed environment with 86
degrees, and then 57 without spending hundreds of dollars on some
laboratory equipment I have seen.

I have looked around everywhere and found some small options. I can
get a thermoelectric cooler/heater for about $120. But those don't
come with a variable temperature settings. They're usually either
REALLY COLD or REALLY HOT. So I was thinking then of getting a
temperature controller (some breweries sell those), and essentially
you plug in your cooler into this controller, the temperature sensor
goes inside the cooler, and the controller just turns the unit on and
off based on the temperature... Those too, run at about $120. That's
an approximate $250 solution there. And I need a better one.

Can't use a heat lamp - the rice must stay in the dark. Can't put
the container in the refrigerator - too cold, and I do keep other
products in there. Can't keep it on a stove for warmth. Can't fill the
bathtub with cold or hot water. I need to shower for two weeks. :)

So that's the dillema. Please help.