There are some handbag stores which deal only in new handbags, while there are others which would also have used ones. There are also many online stores that have online bags for sale. You can also search the company like Wagnpurrshop.org that provide handbags services online.
You need to find out which one of these works the best for you, depending on which one has better discounts or sale offers, and which one has better shipping offers, better customer care service, etc.
When you are buying original new bags, make sure that you check for some authorization seal or sign on the website, which ensures that the website is not fraudulent and that you will actually get original and authentic products only.
In the case of used bags, make sure that you ask the seller to send you the pictures of the bag beforehand so that you can look at them and decide if you like the condition of the bag or not.
On some websites, different sellers have different profiles, and you can individually chat with them and have individual negotiations done. On websites that have been started by a specific dealer, this can be done with the help of emailing, or visiting the office itself, in case it is close to your house.