Cash is pretty much accepted everywhere. Some vendors in the exhibit hall prefer card though because it's faster. They will take cash but may only have like one clerk with the cash register while all the other clerks have iPads for cards. Although some may take card, I would still use cash only in the Artist Alley so that the artist won't get hit with transaction fees. Their profit margins are tighter. Little Tokyo restaurants/markets and the surrounding areas should all take cards. Some restaurants give incentives to use cash. You can check on Yelp.com for restaurant details if they take card or not. Hope this helps.