The honest answer is that ISO certification has two separate costs, and most quotes only talk about one of them. There is the cost of building the system, and there is the cost of the certification body that audits it. Knowing how each one works is the difference between a realistic budget and a nasty surprise.
Keuer Solutions is an independent HSEQ consultancy. ISO certification is issued by JAS-ANZ accredited certification bodies, not by Keuer Solutions. We also run SWMS Aus, an online store selling SWMS and HSEQ template packs for Australian trades.