Besides the sensors themselves, what hidden costs should I expect when buying a predictive maintenance system?

DHMSCare has no hidden costs and is priced per plant by equipment and installation-point count. The quote lists the sensor and gateway hardware, the per-sensor platform subscription and the implementation service provided to the project’s needs (implementation is charged as its own line in the quote); custom system connectors or extras beyond your plan are also listed separately. Per-sensor subscriptions keep the start light and let you scale with your fleet, so costs are clear from day one.