The best place to buy a carbon monoxide detector depends partly on your circumstances.
The Best Place for Most People is Online
The most convenient option, and the one that usually saves you the most money, is simply to order them online.
The best online store with the lowest prices is generally Amazon.com (affiliate link) and that's the wisest place to start in my opinion if you already know which type of detector you need and how many your home requires.
Which One Do I Need to Buy?
Here on CMDP we have reviewed the best CO Detectors & Alarms to help you work out which ones are what you need for your situation, and each of the reviews have links to Amazon where you can buy the number of detectors that you need for your home (if you're not sure how many you need then read this).
To Buy Carbon Monoxide Detectors Offline
If you're not comfortable making purchases over the web, then the next best place to go is one of the following national retail chains - click on the link to find the nearest store to you:
After You've Made Your Purchase
Once you have your CO detectors you should read the following guides before installing them:
Don't forget to read our reviews of the best ones currently available before you buy carbon monoxide detectors - click here for details.