Rule One: Model Compatibility Is a Written Field, Not a Memory
The most expensive mistake in parts sourcing is the wrong-model order: a screen for an iPhone 12 ordered against an iPhone 13 repair queue. Every parts order should carry model compatibility as a written field per line item — model, position (front/rear for cameras), and connector generation (Lightning vs USB-C for ports). If your supplier's quote does not state these per line, the compatibility risk sits entirely with you. Our parts wholesale page lists how we state these fields on every line.
Rule Two: Buy Assemblies, Not Components — Unless You Have the Bench
For screens and charging ports, the economics split between assemblies and components: a display assembly (panel + frame + flex) is install-ready with predictable labour, while glass-only or port-only service requires lamination and micro-soldering capability in-house. Shops without that bench capability should buy assemblies exclusively — the per-unit saving on components is lost the first time a lamination fails. See our screen wholesale and charging port wholesale pages for the assembly options.
Rule Three: Sample-Test Every Batch on Arrival
No supplier's QC replaces your own. On arrival, sample 2-5% of every parts batch and test the function that matters: screens (display, touch, brightness), batteries (voltage and capacity), ports (charging, data transfer, microphone), cameras (focus, exposure, image output). A batch that fails your sample is a claim with evidence; a batch you never sampled is a claim with an argument. See our inspection standard for the full checklist.
Rule Four: Pair Parts Supply With Repair Capacity
The parts margin and the bench margin are the same business viewed twice. Shops that run their own bench should size parts orders to the repair queue, not to a bulk discount; shops without a bench should route repairs to a volume repair partner and keep only fast-turnover parts in stock. We supply both sides: volume repair services paired with parts supply, so the bench never waits on inventory and the shelf never outruns the queue.