Where your quantity sits against the 1/5/10/25/50/100/250/500/1000/2500 break points (just under a break is the expensive place to be)
Piece format, paper, and folding or finishing
Data processing, list hygiene, and personalization
Postage class and whether the mailer qualifies for presort or automation discounts
Check before signing
Postage marked up rather than passed through at cost
Presort or automation discounts the vendor keeps instead of crediting you
Data and list fees that scale per record without disclosure
Handling charged on top of inserting
Negotiation levers
Ask for postage as a documented pass-through
Design the piece to hit automation postage rates
Provide a clean list to cut data fees
About envelope, 5x7 pricing
Priced per unit with quantity breaks. Vendors quote steps at 1 / 5 / 10 / 25 / 50 / 100 / 250 / 500 / 1000 / 2500 units, and the per-unit rate drops at each break.
Should I be charged a markup on postage?
No. Postage is a carrier rate. Reputable vendors pass it through at cost and earn margin on printing and services, not on stamps.
What makes one mail piece cheaper to send than another?
Size, weight, and whether the design qualifies for presort and automation discounts. A small design change can move it into a cheaper postal category.