A basic answer without going into optimizing:
Slippers of Battledancing cost 33,750gp
DMG, p42, last paragraph
As a general rule, a new character can spend no more than half
her total wealth on a single item, and no more than one quarter
the total wealth on consumables such as ammunition, scrolls,
potions, wands, or alchemical items.
So you would need twice as much to start (67,500gp)
WBL table (DMG,p135)
11th - 66,000gp
12th - 88,000gp
So you would need to be 12th level, minimum to buy them.
Crafting costs 16,875gp. Assuming the half-wealth rule applies, you'd need 33,750gp
8th - 27,000gp
9th - 36,000gp
So you would need to be 9th level, minimum to craft them.
You would also need Craft Wondrous Item feat, Perform (dance) 5 ranks,
longstrider, cat's grace, eagle's splendor, and 1350xp, all of which you can get by 9th level.
If you want to add a smidgen of optimizing, you can wait until after character creation to buy or craft the slippers, in which case you're not limited by the 1/2 wealth rule. You could also pick up the mercantile (?) feat to start out with more gold.
Good luck.