How should I invest my money once I hit 60?

Solution 1:

As Emerica said in the comments, Crafters are changing in the upcoming patch, (1.0.3) so they are not the best way to invest your money at the moment.

Saving your money up to buy gear on the auction house, while farming for gear.

Farming for gear pre 1.0.3 you will want to spend time in Act 3/4 of Hell, rather than act 1 of Inferno.

Once 1.0.3 comes, you can start farming in Act 1 of Inferno and start getting good gear. As well as acts 2+ being revamped in the future.

A lot of this info is sourced from this post: http://us.battle.net/d3/en/blog/6262208/Patch_103_Design_Preview-6_6_2012#blog

Once the real money auction house goes live (currently projected to be 06/12/12) you can always sell some of your gold for real money if that interests you.

Solution 2:

Others will provide more meaningful answers about the best use of your coin to improve your character and amass further wealth, but since you mentioned it, I wanted to say a word about stash space.

I long ago learned that in most video games, having available inventory space is functionally equivalent to happiness. Having lots of bag space will save you time on town trips, help you stay organized when buying and selling, let you save all the gear you want for alts, save any sentimental items you may accrue, and more.

So by all means invest in the artisans, the auction house, getting a few razzle-dazzle gems that'll last you for ages. But an investment in at least some additional working room in your stash will never be wasted. ;)

Solution 3:

Don't bother with leveling the artisans at this time, for progress in Inferno you're going to want a high DPS weapon, lots of health and resistances, and then your primary stat. It would of course help to know which class you're playing but this is a general outline. Spending money on the artisans is expensive and there are better items on the auction house until you find rare recipes.