The $30 t-stats work to an extent, but they are not very reliable or accurate. A friend of mine uses a Reptitemp 500R (also around $30), and he has had some problems with temperature fluctuation. I would recommend using a $30 t-stat or a rheostat (dimmer) only temporarily until you can afford to upgrade. Johnson Controls and Ranco thermostats are each $80 on Reptile Basics. I personally use the Ranco and have never had any problems with it.