With a bulk mail permit from the USPS (around $250 annually), you are entitled to explore the rather complicated world of reduced cost mailings. there are lots of guidelines tht determine what class of mailing and the costs. This is not for 30 or 40 pieces, but 200+ in that neighborhood.
When we do mailings, we address it to “Our Neighbor in Grantville, Georgia 30220”. we call the postmaster and ask how many addresses are in each mail route; we have 4 routes. I then bundle enough for each and every person on those routes I want to hit (and a few extras for mistakes) and take them to the counter, labelled with route number and total addresses. they charge you by the piece, so only count the addresses in the route and not the ‘extras’.
This is known as “saturation mailing” or DDR. We pay about 17 cents per piece for 1 ounce letters. there are BUNCHES of levels and classes of bulk mail.
www.usps.com will have a publication available with details if your postmaster doesn’t have it. They are very precise about labelling, sizes, bundling and the like in order to get your discounts . . . you’re doing the work, so you get the discount.
I hope some of this helps. If this is a one-time venture, you way want to go to a direct mail contractor in your area and let them charge you an extra few cents per piece to mail them for you.