Hi
I would suggest a custom solution for your needs, however to provide an accurate time/cost I need to carry out further discussions with you.
To qualify myself, I am certified developer having 10+ years of experience working in various business domains and helped creating Inventory systems in the past. I have a clear understandings of what is required in term of Inventory in general.
Please get in touch to discuss further, before I can give you revised final estimates.
Regards
AZ