I think this is a very recent project but I can't see any dates on the HackHD site. This simple PCB features a 1080P 30FPS camera which can be controlled electronically and records to an SD card. The website is very bare with some details about the PCB but no example videos. Thankfully there are some good examples and comparisons on Youtube.
The site offers to sell you a starter kit including PCB, battery, memory card and some other components for US $140 (about £90) which seems pretty reasonable.
808 Car Key Micro Camera (http://chucklohr.com/808/)
While Googling for reviews of the HackHD I came across a thread on a paintballing forum which was discussing the HackHD. One poster in this thread suggested that they would prefer to use an 808 Camera which supposedly only costs USD $38 for 720P video. A bit more Googling turned up the link above which describes the 808 camera as a line of cheap HD cameras out of China. The most recent edition is the #18 model which supports 720P 30FPS video and is available for around USD $36 on ebay.
The same ebay sellers are offering a cheap 1080P video camera but this thread suggests that the video capture is unreliable.
Electric Imp (http://www.electricimp.com/)
Electric Imp is a micro controller with a wifi connection in a standard SD card form factor.
The card will retail for USD $25 and there are several interesting development kits which cost between USD $7 and $25. This is a very recent project so the products haven't actually been released yet but are due very soon.
I'm particularly interested in this as it is impressively cheap for a wifi solution.