Freeze the specification first
Align material, dimensions, construction, artwork, finish and packing before comparing unit prices. Put differences in a separate column.
Normalize quantities
Compare the same saleable unit and total quantity. A price per sheet, per pack, per piece and per set cannot be compared without the conversion.
Check included work and parts
Record printing setup, samples, lids, screws, inner packaging and carton labels where applicable. Ask which items are included and which are extra.
Confirm delivery and timing
Use the same destination and delivery scope. Distinguish sample timing, production timing and transit estimates, all subject to the agreed order.