For example, getting a trader in:
- the wild or small quest hubs or small town but the trader isn't shown on the map until you click on that town - would cost 10 000 gold (think, Voljar Meadery, Koeglin village wayshrines.),
- a small city (quest hub or has some point of interest (bank, crafting stations, Mundus stone nearby etc) - 50 000 gold (think Fort Amol, Kragenmoor, Hoarfrost Downs, Firebrand wayshrines),
- a big city (province/zone capitals) - say, 100 000 - 500 000 gold depending on the zone and the layout of a city (think Sentinel, Shornhelm, Baandari Trading Post etc.)
- DLC cities - they are very actual when DLC is just released but then become less popular after. Also some are big and have everything (Orsinium, Hew's Bane), while others are very limited (Anvil, Kvatch) - ~100 000 - 1 000 000 gold depending on the city and how long ago the DLC was released and/or how popular it is right now.
- Capitals and elite cities - these are places where most players hang out looking for groups and chatting: Stormhaven, Elden Root, Mounrhold (they have undaunted camps as well as big quest hubs as well as banks, crafting stations); Craglorn, Rawl-kha (very convenient and traditionally has lots of players) , maybe Orsinium? (lots of people there because of dailies, well that's why prices "overlap") - starting 1 000 000 gold.