I would love to know about the web site! Many companies will donate things to teachers, such as office supplies. For instance, I have gotten used binders from businesses before. Sometimes when I buy from sellers on ebay they will give me free shipping or throw in free product or extras.
Borders and Barnes and Noble bookstores have permanent teacher discounts, and special nights during the year where teachers get an even better deal. On sites that sell books or textbooks, or computers and technology, teachers usually get a better deal than most. Apple computer company gives teachers a discount on almost anything they sell in terms of hardware, and have done so for decades. Microsoft too.
I have no idea whether you're concentrating on secondary or elementary teaching tools, but my experience is that their needs are quite different. That may impact the ideas you get as well as how you design your website.
As a drama director, I always appreciated fabric stores like JoAnne's Fabric which offered significant teacher discounts.
Often, newspapers will offer free delivery to classrooms for a period of time to facilitate some units of study.
Another good source for $1.00 books is Dover Publications at:
Are you after resources or just objects that can be purchased? There are many sites that offer great resources that can be accessed on line and then printed, and I would think that enotes actually tops them all, but a quick google search would find many others that you might be interested in.
Townsend Press has a number of free things for teachers and students. They also offer some great books for $1 each, which is great when you need a classroom set. http://townsendpress.com/free.aspx
Teaching Tolerance has a number of free resources as well. http://www.tolerance.org/search/query.html?col=test&qt=free
Also, there are some links to great sites if you just google "websites for teachers"