@Wayne Tam  Her are a few ideas for saving money.Use your ink jet printer but buy an ink refill kit, you will refill a cartridge for $2-4, some printers will recognize if you put the same cartridge back in right away so keep 2 or 3 and rotate them through.Instead of using the legal pad paper buy some plain yellow photo paper, write your letter on white paper WITH LINES, then copy that in color mode over to your yellow paper, with a little running you should be able to get the lines to print too.Someone here on BP advise that there is an app that will turn your personal handwriting into a font for your computer, I have not tried that yet but it has to beat hand addressing 100's  of envelopes so I will try it soon.  

You should rotate the areas that you mail too.

Whatever you could afford, rotate the marketing pieces to the same list.

When you said to rotate the type of letter you use do you mean that every person on your list should receive multiple types of letters?

I made 7 post cards that I will be sending out every 30 days in rotation.

When I ran TV before I would run a rotating line up of two programming types.1) Jerry Springer type trash shows...2) Cable News Shows.

Most look at the .35 cents or so and think great price where in reality they shouldn't look at any number other than that of conversion rates, ROI and more importantly the cost of the infrastructure for the capture and fulfillment systems of the mail types.In short if I were only sending a few thousand pieces on a rotation I would send Yellow Letters followed by a Zip Letter/Check and then a postcard.