We have 1 vendor price on record for blank 3-part hardback carbonless general invoices - 4 1/4" x 7" - 500/box. Two more independent vendors are needed to establish a benchmark range.
Submit your quoted price to help build this benchmark.
Usually a specification or finishing difference, not the core work. Ask both vendors to quote the identical spec and the gap normally narrows.
Related variants of this product are tracked as separate benchmark lines. Match the spec before comparing quotes.