Wireless Mice and keyboard combos are great, as they use one USB dongle instead of two with standard cables. But, if you like using a cord, you can find combos in most electronic departments between $25-$50.
There are a few things you should consider before purchasing a new keyboard for your computer. These pre-purchase decisions can help you be not just more proficient, but the type of keyboard and mouse you select could be bad for your wrists and hands.
Here is a list of things you might want to consider:
Some mice are built better for longer usage durations and comfortable work situations. Other mice are built with lots of buttons for gaming purposes and have fancy lights. Choosing a mouse is a little less important I find that people literally choose a mouse for 2 things: either for asthetics such as graphics on the mouse or colored lights on the mouse.
Conclusion
Everyone should consider what suits them best, prior to purchasing a keyboard or mouse in order to get the most enjoyment or productivity from their mice and keyboards.