Try this as a lead-in. Adding bulk and mystery to an envelope helps increase your chance of opening and getting read. With that in mind and frugality always important, try this neat promo. Tape two pennies side by side t the bottom of your letter. The top intro can start something like "I want to get my two cents in to tell you why you should buy from me (ro whatever selling message makes sense)" as a coherent intro. The important points here are to (a) add bulk to the envelopes without costing too much (it's going to cost more in labor to tape the coins down than the actual coins themselves) and (b) tie the coin mystery into your selling message ("two cents worth", "for pennies a day", "return these 2 cents, along with your check for $9.98 and I'll send you this $10 item"). Okay, maybe that last example doesn't have much selling punch, but I'm sure you can come up with a better tie-in. Add the bulk to your envelope, create a little mystery before it's opened, and your message will come through, if for no other reason than to find out why you've send the reader some free money.