You can buy Sovereign Gold Bonds easily through internet banking of SBI, ICICI, etc. You can also buy it through demat account and post offices. Buying online is preferred as the application process is simple and you get a discount too.
Sovereign Gold Bonds Series I (FY 2020-21) is available for subscription from April 20, 2020. The price per bond is Rs 4,639 (4,589 if bought through digital mode). You can invest if you anyway wanted to invest in Gold for 6-8 years.