If I were in your shoes I would start by reading this short article: http://ecopreneurist.com/2009/07/02/10-great-cheap-green-office-supplies/ and the related articles posted within it in order to get the most green for your green. The article has links directly to several green product suppliers for your convenience as well.
Many national office supply stores now offer eco-friendly products so you may not even have to change who you’re currently purchasing supplies from. If you do not use one of the national supply store-front based businesses, you could call your bulk/direct supplier to ask them to offer green products which will help push the movement forward by bringing to their attention that it is in growing demand.
If you need further information or guidance, feel free to contact me. I’d love to help!