By far the biggest advantage of creating and managing your own database is that you are less reliant on 3rd party databases who either are or will become more costly as demand increases and who have a habit of changing the operation of their platforms to suit their own business requirements. The good new is that with todays technology databases to house and assist manage your customers details are extremely cost effecient. 

Depending on your POS system you may find you have the database that will collect and update your customer database and maybe give you some contact interaction. If not – initially I would commence with a software program that is free in the lower usage area as they have most of the attributes you would need. You will find, if you select wisely, that your database will transfer into more complex software should you wish it to at a later date.