Hi, I would strongly advice that you go with the instagram/fb promotions tool but if you want to spend more the right answer would depend on your location and your store category as it’s crucial to choose the right influence that targets your store audience.
another good choice is choosing a website that provides affiliates programs which will offer coupons on your behalf that can be promoted by several people whom registered with said website.
and the last option is finding an agency that works with multiple influencers in your area, the agency will suggest a number of influencers based on your budget and manage your promotion campaign.
i hope that helps