Is an iPhone 15 Pro Max (Grade A) for SAR 3,500 worth it?

Hi everyone,
I found an iPhone 15 Pro Max (Grade A/refurbished or used in excellent condition) for SAR 3,500 from an online store(Jarir), and I’m thinking of buying it.
Before I do, I wanted to ask:
Is SAR 3,500 a fair price for a Grade A 15 Pro Max, or is it overpriced?
Has anyone bought a Grade A iPhone before? How was your experience?
What are the biggest risks when buying a Grade A/refurbished phone online?
What should I ask the seller before purchasing? (For example: battery health, original parts, repair history, warranty, carrier lock, etc.)
Are there any red flags I should watch out for?
If you’ve bought from this kind of online store, was it reliable?
I’d really appreciate any advice before I spend this much. Thanks!