If you're running a business, you probably use good ole' stamps and envelopes for a variety of purposes: checks, invoices, direct mail, letters, etc.  The last time I sent out a direct mail piece, it consisted of a personal letter, a small trifold brochure, and a business card.  I sent 1000 of them, which translated into two boxes of 500 envelopes from Staples.  The cost, just for envelopes?  About $70.