I need to implement barcodes to be used in inventory tracking at a warehouse.
What type of barcode should I use?
What economical software is in the market that I can use for the implementation?

You haven't received an authoritative response yet, so I'll throw Wasp Barcode (http://www.waspbarcode.com/) out as a possibility. The type of bar code depends on what your system needs to accomplish and any business partners you need to interface with. See Introduction to barcode - Bar Code Symbologies (http://www.taltech.com/resources/intro_to_bc/bcsymbol.htm).