peripherals are extremely dependent on personal needs. Have you tried both a laser and optical mouse, and a mechanical and membrane keyboard? If not you should do some research into those to decide which ones you prefer. Remember that there are many types of switches for mechanical keyboards that feel different, and mice have different grips such as claw, palm, or fingertip.
Also there are features on each one that you might want or not care about such as media or macro keys on the keyboard and buttons on the side of a mouse. Either way with a $100 you will not be able to get a high end version of a keyboard and mouse so it will be one high end one low, or both medium.