Mass Spectrometry is quintessential technology, and as such there are many platforms available -- from triple quadrupole to hybrid quadrupole/time-of-flight (QTOF) devices and others depending on the intended application(s). When shopping, key metrics to consider are: resolution, sensitivity, speed, throughput, and versatility. New models can offer enhanced performance, efficiency, and ease-of-use -- while used models may provide suitable performance at significantly lower prices. Consider the condition of the system components, although systems are typically tested to manufacturer standards. When purchasing, also review the compatibility with upstream devices such as LC systems and software support, from either the manufacturer or vendor.