This is really a combination of other contributions that, with a small addition, will make it possible for you to let your supplier's maintain their products on your site themselves.
There is a lot of hard work here if you have a fresh install of osCommerce, but it's a sought after feature.

The supplier will be able to:
- change the properties you want them to. (Including their price to you)
- add their products if you want them to. (You will have to approve and set a selling price for the product yourself though before they go public)
- delete the products they supply if you want them to.

Support thread is here: http://forums.oscommerce.com/index.php?showtopic=258847

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