Use the Costco credit card
Costco products can only be purchased with a Visa credit card. So, if you want to be able to buy the things you want and save some money in the process, get the Costco Anywhere Visa Card by Citi. Apart from other perks and benefits for using the card other than at Costco, you also get 2% cashback on everything you buy from Costco and Costco.com.
Not to mention that at Costco pumps and other eligible gas stations, you get 4 percent cash back!
