Wireless security cameras are much easier for the do-it-yourselfer to install than wired security cameras that involve digging into the walls to install wiring. The technology does tend to be more expensive, though. How much? As with many things home security related, it depends a lot on how exhaustive a system you want to install.

For a complete wireless video surveillance system that monitors the exterior entrances to your home (and possibly some interior areas as well) and is hooked up to a monitored home security system, expect to pay thousands of dollars, even tens of thousands for top of the line equipment.

If you're not ready to make that kind of investment, or just want to try maybe a single wireless security camera hooked up to a TV monitor/VCR recorder or computer, you can enter the field at a significantly lower cost. You can always start simple (read low cost), decide how well you like the technology and how well it works for you, and then move into more sophisticated equipment and coverage.

X10 has a color Wireless Video Camera for under $100 and there are a few more listed at Amazon.com in the $100-$200 range.  Examples are the SVAT Wireless Home Security Camera and the Sylvania SY4225 2.4 GHz Wireless 5-inch Black and White Video System which transmits in black and white but comes with both camera and a small tv monitor.