Scrap max stack is 1000.  How can I charge 5000 scrap for an item, for example?  It will only let me charge 1000 max.

The easiest way would be to just edit the data file after saving the vending machine.

• If the vending machine is not spawned by a plugin, then edit oxide/data/CustomVendingSetup.json file and reload Custom Vending Setup.
• If the vending machine was spawned by Monument Addons, then edit oxide/data/MonumentAddons/<profile>.json for whichever profile spawned the vending machine, then reload that profile or reload Monument Addons.
• If the vending machine was spawned by the Talking NPC Vendors plugin, then edit oxide/data/TalkingNpc/VendingMachines/<profile>.json and reload Talking Npc.

If you encounter any issues, such as the scrap stack not having the full amount when you open the edit panel, that's probably due to whichever stack plugin you are using. Let me know if you see this, and I can make improvements to Custom Vending Setup to allow one stack.

Long term, ideally you shouldn't need to edit the data file for this use case, but it's difficult to say how the plugin should influence stack size in the edit container since there are at least 4 popular stack size plugins in circulation, each with different designs, so compatibility is not straight-forward.