Yes, you can buy skins using your store balance;
1. Simply head to the store page and add the desired skins to your cart
2. Advance to checkout and complete the purchase

3. Approve it on Steam
That's it. Enjoy your new skins!
​
*If you don't have enough store balance to complete the purchase, a pop-up window will appear where you can top-up your store balance using your preferred payment method.
​