I recently purchased these gag security cameras online and thought it was very funny for the homeowner on a budget. The red light blinks when it detects motion, attaches to the wall with a 2-way tape sticker and costs $3.90. Mainly used as a deterrant. For those who wish to spend a little more and get serious with their security, try engaging Cisco or buy full surveillance equipment online from http://www.dinodirect.com/security-systems/. The below system costs around SGD $500, free worldwide shipping (for most items, pls check)!
* I purchased several items from Dinodirect but only half of my order came. Couldn't reach the company for response on the remaining order. I think the company is another one of those China PRC based entities that doesn't offer recourse. Safer to not buy from this site ;)