If PCR is a frequent activity in your laboratory, then a good way to save time is to make a master mix. A mix for PCR usually contains buffer, deoxynucleotides, and taq polymerase in at least 2x concentration. Then, at the time of PCR, it's very easy to make up set up a reaction with template and primers of your choice. Biotechnology tools vendors have picked up on this trend and now offer a variety of prepared PCR master mixes. These products offer all of the convenience of a home-brewed mix, plus some high tech perks such as PCR-enhancing additives, dyes, and genetically optimized DNA polymerase. As well, commercial quality control helps prevent the loss of time and material that can result from an error in preparing a master mix.
However, neither is a PCR master mix a one-size-fits all solution. Different types of reactions and different purposes require different components. Your application may need a different dNTP composition, or you may have special requirements for real time PCR or another specialized application. If you're looking for a master mix to meet your needs, it's best to start with an idea of what is optimal for your reaction. Then shop the vendors on this page to see what best meets your needs.