Gold, Flying mounts, Cold weather flying conundrum:

[nomenquis]

if you think that is bad, my whole team has regular level 30 mounts only.

So question... do you need the fast flying mount to get the cold weather flying mount? so... 700 + 1000 + 5000 + 1000 per person to fly in northrend? or can you drop that 5000 one out of the equation?

You don't need to buy the 5k skill.
Cold weather flying and riding skill are independent of each other i think.