Capital equipment purchases are one of the best opportunities to negotiate. Since you're already coordinating with the sales rep to confirm specifications, that's the natural moment to ask for a discount. Start with a strong ask, expect some back and forth, and aim to land somewhere in the middle.
Bulk orders and recurring purchases deserve the same treatment. Any vendor receiving steady, repeat business from your lab should be willing to extend a loyalty discount, whether that applies across their full catalog or just the items you order most often. This same logic applies to your top five vendors overall: consistent volume is leverage, and it's worth asking what they can offer on it.
The exception is urgency. If you need something tomorrow, that's not the time to push for a deal. Order only what you need immediately, then negotiate on the remaining quantity once the pressure is off.
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