Since you are somewhat of a scrounger, find an old stove that some one is tossing out. From this, snag the burners and reflectors along with the sockets and the wire with the high temp insulation. You can also harvest some of the oven insulation.
The oven will have a thermostatic control. This reads the temp with a thermocouple and then switches the oven on when it is colder that the set point, and shuts it off when it gets up to temp. You can snag these components also.
The problem you may have with the oven controller is that the actual temps are higher than you might want and lower than you might want.
Controlling an electric element with a simple thermostat is like trying to control the speed of your car by flooring the gas pedal or not with nothing in between. When the element comes on, it goes from cold to very hot to send its heat into the area around the element. Once it is shut off, it still sheds heat so the oven temp over shoots.
If you had a switch to turn the element on and off and could observe a thermometer, you could see that there was a bit of a lag before the temp started to rise, so you could watch as the temp was dropping and anticipate the need to turn on the element a little before the lower limit was reached. You could also cut power a bit before the upper limit was reached so the temp would not over shoot the upper limit.
Depending on how alert you were, and how good your sense of timing was, you could do a bang up job of holding a steady temp in the oven.
But this would take a lot of time and take all the fun out of things so this is why they invented the PID. Here software keeps it's eye on things and mans the switch. So what you do is place the temp probe in the oven right where you want the temp to be and plug that into 2 connections on the PID, then you stuff another temp probe into the meat and hook that up to another 2 connections on the PID and then hook up 2 more connections to the electric element.
Now you are flying on auto pilot, Well almost anyway, you probably still need to stoke the smoke generator from time to time.
I think if you took the round stove top elements and reflectors and mounted them in the bottom you should be in business.
