So WoWhead put out a table for how much all upgrades will cost, so I thought I would create a list of what that translates into for keys:
Currently it seems each key gives 62 bonus flightstones for timing it, odd number that could be influenced by the key level given I just did a 10 to get my references for this, and 25 fight stones for doing the key, for a total of 87 flightstones.
For melee one handed weapons, that translates into: 23 keys
For caster one handed weapons, that translates into: 35 Keys
For melee two hander weapons, that translates into: 45 keys
For the Razageth bow, that translates into: 55 keys
For Fyr’alath, that translates into: 44 keys
Finally, for Nasz’uro, that translates into: 34 keys
Do with this information as you will, all of these were rounded up and assumed you only did keys to obtain your flightstones, yet some of this to me seems to be a bit steep. Especially given some classes dual equip and will have to do twice the amount of work in comparison to other classes.