Unlimited money
Coupons will go away after you log off. Make sure you have at least one coupon. Go to the W shop. Buy something that is too expensive. Buy as many as you have coupons. Put the coupon(s) on the item(s) then remove the coupon(s). Exit the W shop. Look at how many coupons you have. You can repeat this as many times as desired and use them on anything.