HELP FINDING A PHP/Mysql ERP/POS SYSTEM

I have been searching for ERP system that runs on PHP/Mysql for a
med-large sized business.

Most of the ones I have found are pretty cheesy and don't do everything
a ecommerce company would need.

Looking for
1. Ability to maintain inventory
2. Ability to drop ship a order
3. Import orders from a already created ecommerce website.
4. PHP Archetecture
5. MySql backend
6. Software company has been around and has some good demo/references.
7. Customer Management
8. Add QTY pricing
9. Special Pricing
10. Coupons

Does anyone know of a good company to handle this? It is kind of
disappointing to me since I am a php programmer. But I don't want to
recreate the wheel.

Thanks in advance for your advise,