The importance of defining your lot structure
This category is relatively easy to define but needs to be fairly sizeable to attract the participants. There is a volume and delivery requirement with a quality which needs to be met. The higher the volume, the more ability there is to negotiate on cost. Leaving yourself options for dual sourcing by a careful Lot structure might be a way forward. When there are several operations required, you could examine splitting this out into several Lots but also keeping a Lot for the combined operations. This will generate more options and improve liquidity for the final Event.