Garmin are one of the leading manufacturers of GPS computers for sports tracking and cycling. They also manufacture and develop a range of GPS navigation tools for the auto, aviation and marine markets.
Garmin was founded in 1989 by Gary Burrell and Min Kao. Their UK base is in Southampton and they currently have a sponsorship deal running with the local football team Southampton FC. They also sponsor the Cannondale-Garmin pro cycling team that includes riders such as Ryder Hesjedal and Andrew Talansky.
When Garmin bought Dynastream, the company that invented the ANT+ wireless protocol technology it allowed them to use that technology to stream data directly from cycling products such as power meters and cadence monitors directly into their Garmin cycling computers.
You can find Garmin Edge products at most cycling retaillers like Evans Cycles and Chain Reaction but you can also find some cheap garmin deals on Amazon.