No it's not mandatory for you unless you cross the threshold limit..... the compulsion to take registration is with regard to inter state supply of goods and not purchase....
Hi, Mr. Ganatra Prakash. It's mandatory to have a turnover of 40 lakhs to get a GST Number and if your turnover is below than 40 Lakhs then you no need to worry about the registration of GST. You can easily buy the clothes from any state and sell in any state of India. have also a GST Number and I registered online for GST from TradenFill at a reasonable price.