Where your quantity sits against the 1/5/10/25/50/100/250/500/1000 break points (just under a break is the expensive place to be)
Materials and specification of the item
Quantity and where it falls against a vendor's price breaks
Finishing, customization, or add-on services
Check before signing
Setup or one-time fees charged per unit or repeated on reorders
A specification quietly changed from what you asked for
Rush surcharges applied to a standard timeline
Line items bundled into a single total so individual prices can't be compared
Negotiation levers
Standardize the specification so vendors quote like-for-like
Consolidate volume or designs to share fixed costs
Offer schedule flexibility in exchange for a better rate
About business cards (500 qty) pricing
Priced per unit with quantity breaks. Vendors quote steps at 1 / 5 / 10 / 25 / 50 / 100 / 250 / 500 / 1000 units, and the per-unit rate drops at each break.
Why do two quotes for the same item differ so much?
Usually a specification or finishing difference, not the core work. Ask both vendors to quote the identical spec and the gap normally narrows.
The same product family is tracked in 16pt stock, 14pt stock, 19pt stock. Quotes are NOT interchangeable across variants, so match the spec before comparing.