I haven't used on but there are differences in quality among switchers but here is an inexpensive one.
[Link: monoprice.com]

For better quality look at Inday You would need two units, one for audio and one for video. Not under $100 though but reasonably priced for the performance. Sometimes cheap is just that. Some info.
[Link: inday.com]

Component switcher
[Link: inday.com]

audio switcher
[Link: inday.com]