Carbon dioxide detectors do no seem to be widely available. Carbon monoxide detectors are quite common and required for homes in some states. One should never purchase this type of equipment secondhand as it may not work when needed.
One can purchase secondhand hardware from Northern from the 'freeads' website. One can also buy such items secondhand from 'Adpost' and 'Great Northern Traders'.
One could purchase a secondhand iRobot Roomba 500 series on several different websites. A couple of different websites that one could purchase a secondhand iRobot Roomba 500 series are Amazon and eBay.
There are many places where one can purchase a counterfeit money detector. A good place is the website "Amazon" or the website "eBay" to purchase a money detector.
One can purchase a Minelab metal detector as a precious metals show and convention or online at Amazon or any metal detector website. Plus shipping of course.
One can purchase a secondhand daybed bedding set when one goes to Kijiji. One can find a couple of choices and price varies depending on the design, condition, and material.
You can purchase a moisture detector at your local Lowe's or Home Depot store. You can also purchase one online from the Amazon website and have it shipped directly to your house.
You can purchase a secondhand power juicer deluxe online from websites such as eBay and Craigslist. You may also be able to find a secondhand power juicer deluxe for sale in your local classifieds.
One can purchase an underwater metal detector at a local all round hobby store or at a metal detector store. One can also buy one on various webshops like Amazon or eBay.
One would purchase a camera detector mainly for reasons of security and privacy. A camera detector can be a useful tool in determining whether one is under the surveillance of an outside third party camera.
One can purchase a secondhand BMW 3 series online through sites such as Ebay motors. They can also be found through private sellers in publications such as Auto trader.
Toro does not sell secondhand snow blowers, but one can purchase a Toro snow blower used from a previous owner. The best place to look for one would be Craig's List or Ebay.
In order to purchase a secondhand Pindad SS2 V4 (also known as "Senapan Serbu 2" or "Assault Riffle 2") one should check with a local gun dealer or gun shop.