Most supermarkets have an aisle where they display greeting cards. If you time this right, usually after a holiday, you will run into the greeting card company representative clearing out the cards of the holiday that just passed. If you ask nicely, and also depending on each company’s regulations, they may give you the extra odd envelopes left over from the cards. It can’t hurt to ask! These envelopes will come in handy for many uses in addition to mailings plus it is another way to recycle!