Like I said, I made $$ leveling up every single craft, but that was a little while ago and some of the materials are more expensive now. But you should still be able to do all of that for much less than you have. Getting everything to 15 should be really cheap since all the materials you should need are sold by the guild vendor for next to nothing. After that, I would say not to worry about a gathering classes unless you hit a point where the necessary materials are just far too expensive for you to continue.
The one exception to this is if you want your retainer to be a miner to help you making items to spiritbind. While I hate mining for myself, it is nice to be able to send the retainer out to gather all the necessary materials I need for crafting my own jewelry if I want to spirit bind. If you want to do this, then it would make sense to level up your mining also, since your retainer's level is limited by your level in that class (so you need a 50 miner for your retainer to be a 50 miner). Of course, that's 1 more thing to level (not including needing to level up your retainer too).
As far as XP vs. money, worst case quests will still give you 50% xp of the maximum so you're not losing *that* much. You *usually* want to avoid anything that says triple because those will be the most expensive. Courier quests will often be your best bet (especially if you have a free aetheryte destination) unless it requires particularly expensive materials because it still gives you a lot of xp (~90% of a triple turn in) but you make fewer items. The only problem with those can be travel costs between the Quest Giver in the main city and the Quest Receiver out in an outpost somewhere, but that can be mostly negated (see below). But in general, just use the link I provided (the values for those are still mostly correct) and the market board to compare the material costs of creating the item vs. the amount of experience and the rewards you get in return to figure out the cheapest way to level.
Mitigating courier travel costs:
Set your home point to the main city where the Quest Giver is. Set a favorite destination (use your free destination if you have one) to the outpost wherever the Quest Receiver is. Get the quest from the main city, teleport to your favored/free destination where the Quest Receiver is and turn in the quest. Then switch to a level 1 job (any level 1 job, a DoH class will do) and go get yourself killed. You resurrect back at the main city for free and can get the quest again.