There are many websites where you can buy plants and other gardening products. You have to just write an online gardening store on google and google will give you all information. But in my opinion, you must not buy online because:

1. HEALTH: You can buy the plant which you think is the most healthy when you buy from nurseries.
2. BETTER DEAL: If you buy offline you can negotiate with the seller and can save much. For example, vermicompost online is approx Rs 80 per kg but I bought 7kg for Rs 100 form plant shop.
3. ADVICE: If you buy from sellers then you may ask them every question related to your product or plant such as the right way of seedling, watering fertilizing, harvesting, etc. Also, they may share their personal experience with you.
4. NEW TECHNOLOGY: If you buy offline then the seller may tell you some new techniques or new products which you may lack online because before coming online the products are sold offline to have feedback and then they come online.
5. OTHER PLANTS: You may have not seen some plants online which may be available in our areas. So, if you are a plant lover then you should visit frequently to the nurseries either coming from work or on holidays. This will ensure that you don't miss such a rare plant that may be available there and someone else buys that before you.

So these are personal experiences which I am sharing and therefore I do not recommend online shopping unless the plant or product is not available in your area. And the nice thing is that what you may be searching online may be available offline.