Search the stores
First of all, you have to find the stores which deal in different kinds of hardware equipment and motion detection instruments. Usually, the big stores have departments of hardware tools and equipments where you can easily find your instrument by doing a little research. However, you can also seek help of a salesperson in the store to find your equipment.
Search in second-hand goods stores
If you cannot afford to buy a new radar motion detector, you will have to search it in the stores which offer second-hand goods. It is not very difficult to find such shops, but it is quite hard to find the right equipment from them. At first, you will have to conduct some vigorous research for shops which provide second-hand goods from where you can buy the radar motion detector. After finding a good shop, you will have to find the right equipment. Test the radar motion detector at the time of purchase because no guarantee is provided on second-hand goods.
Search in exhibitions
Radar motion detectors are also being sold in different exhibitions related to hardware equipment and motion detecting instruments. However, you will have to keep the time and venue of the exhibition in mind in order to get your radar motion detector.
There are many firms which provide radar motion detectors online. All you have to do is a little research on the internet. You will find many online stores which are providing brand new as well as second-hand radar motion detectors. Besides, you can also get the detector directly from a seller who has an account on online market like eBay.