Not too cheap, because charity is for suckers, but not too much so people actually pay?
(TBC mage here, so may not be “classic accurate”)
2x rune cost will keep you busy.
Many times got a rune(s) and a tip.
I’d watch trade/local as you level and go from there. My guess is each server will settle on a price range that works for them, but may not be the same as the next server.
Cheaper than flight master, more expeneive than rune cost.
Just like real life, economy varies server to server. See what everyone else is selling for and decide from there.
The magic of supply and demand works out a fair price, which depends on the server. Sometimes it even depends zone to zone!
I charge 1g for everything. 1g for portals, 1g for 3 stacks of food, 1g for 3 stacks of water. Only time I charge more is if the server crashes for more than 15 mins and everyone’s food/water disappears. Can bump the price up to 2g due to scarcity. Some mages horde side also hang out in Kargath to charge 2g for portals due to it being far away.