I want to build an e-store with oscommerce where multiple stores(good sellers I have agreement with) can login and control their own stock(insert,edit,etc) and display them on my e-store for customers. Any ideas how to modify oscommerce? any addons or extensions?
I'm not sure how easy it would be to mod OSCommerce to manage something like that. There may be existing contributions, or you might be able to modify the code yourself manually, but it might be a fairly large task to setup.
It might be worth looking into a different platform to build that on, perhaps something like Wordpress with the WP eCommerce plugin, or the newer Jigoshop or Woocommerce.
Using Wordpress, you'd be able to install seperate plugins for user management which would give you the ability to restrict certain products/categories etc. to certain users, essentially limiting each specific client to a particular area of your store.