Let’s address the Elephant in the room.
That long quote from your AV Supplier detailing and pricing every item, projectors, stage equipment, signage, technicians, mixers, lights, cables, every nut and bolt, being hired per day.  Additionally, extra costs for staff if out of hours for the standard working day.  

The total Price at the bottom of the long quote can sometimes come as a big surprise, for instance, £22,000 WOW! (Someone’s wage per year)

Just check that quote again to see if you can reduce some items – couple cables, microphones, bounce back and forward with the AV supplier few times to reduce the price down a little, of course ask for the repeat business discount. There you have it, final price £18,399 WOW! Great knowing you saved a few thousand pounds this time round.

Let’s face the truth there is no AV supplier doing any different they all do the same every time. Wouldn’t it be a perfect World if you could just say “I want a full conference set for a fixed price, that can be £10,000+ lower in price”.