Hi there,
I am in nearing completion of a management system that I have built using php,mysql etc. I am Based in the UK, Currently the system has been built for a computer spares company, it can be easily and quickly adapted to your products and channels, The company I'm producing this for had a long term plan to sell this.
The system has a online shop at the front end (Prestashop) and links with eBay, automatically sending and receiving orders and updating stock.
A lot of time has gone into this system, and can be updated/changed for your needs.
If you are interested looking at this please contact me and I can show you the working system.
Kind Regards