You'll have to wait until the pink eye and rainbow appear in the shop. The rainbow will cost 30.000 without discount. I forgot the price of the pinkeye but it was around 7000.
Make sure you equip both the items for the achievement to unlock.
I recommend you get this as soon as possible, because on the later levels you'll hardly be able to buy gear, it's almost all buffs in the shop.
If you need money, equip gear with coin-multipliers to stack up some coins fast.
(at least 37000.)