Cheap and frugal are very different things. To be cheap is to prioritize cost over all else. Being frugal, however, means not spending more than is necessary while still considering quality, time savings, performance, and other factors. An inexpensive stockpot whose handles fall off after only a couple of brew projects is certainly cheap, but to buy such an item is not frugal. After all, what good is a cheap brew kettle if you have to replace it within a couple of months?
It is this philosophy that leads us to take a look at thermometers. Those who are just starting out in brewing will do just fine with an inexpensive (cheap) thermometer. There are several kinds of thermometer technology from which to choose:
The standard-issue alcohol thermometer that comes with many homebrewing starter kits is familiar, cheap, and generally reliable. However, the alcohol inside the glass may have a low boiling point (depending on the type of alcohol used), which means it could vaporize and condense within the channel if not fully submerged. Repeated cycling of this boil-and-vaporize process can cause bubbles to form in the line of alcohol, rendering the thermometer useless. Also, glass thermometers can break easily.