Checks if player has at least 100 gold, then if so gives NPC 100 gold. Don't know if this what you're looking for. Will check out the map later!
What happens if the player spends or drops the gold in between the time you set the flag and the dialog checking for the flag takes place?
I think this is best handled either by Script flags or a different approach. I have not used script flags myself yet so I cannot give specific advice other than to look at GEN_Check_PocketGold scripts and then the matching 'Dialog Variables' from the Dialog editor. It looks like there is an existing value for '50' in GEN_CheckMagicPocketGold, so using that script may be what you want.
Another more convoluted approach would be to create an item in the NPCs inventory that costs 50g and let the mechanics sort out when the player has enough gold to buy it. Then you could catch on the item being added to the player's inventory.
