@briraj there is no exact price of a bonsai tree, full grown bonsai tree can cost you huge as they are very expensive. But i would like to share about my recent purchase of a juniper bonsai tree seed. It just cost me 1 USD from an online store called Ali Express. I dont know if the seed would grow perfectly but one thing is sure, its the technique and dedication of growing a bonsai that will determine how it would turn up. Hope this helps. Are you planning to try growing your own?? let me know