How to generate a unique barcode without using identity or sequence in SQL Server 2012
Why do you feel uncomfortable storing the id yourself?
This is a valid approach for this problem.

You could also use -T272 as a startup parameter to prevent the gaps during id generation.
I read that this could have impact on the performance of the id generation, but I never had no problems in my tests.
See this link for further information: http://www.dfarber.com/computer-consulting-blog/2014/2/13/how-to-solve-identity-problem-in-sql-2012.aspx

Please consider that there are many different types of barcodes. If you use the common GS1-128 for example, you can create alpha-numeric codes to increase the possible combinations and prevent an overflow.