Talking about the HDD it isn’t a special thing more ever cheap and you can get it easily anywhere in world. something to take in mind is that as of cheap I mean for consumer level HDD i.e SATA and above that you will find enterprise level i.e SAS although the difference is that they boost more memory, RPM & more support from company than consumer one.
Taking this cheap memory in consideration you will get huge memory capacity for bucks and ferfecto for storing you large data. so saving some money on other component you can buy good HDD for rs.4000 to 7500 price range for 1 To 2 Tera bytes.