The absolute only idea that I had which might work is to provide businesses with 100% free automatic (rfid or whatever based) inventory systems of whatever size they need. Yes, that is a large expense.
However, in exchange for the free inventory system, you get access to their data and the ability to post it online. You give people the ability (but don't force them to) buy the item from their mobile phone/computer quickly and easily, so when they show up they have a zero balance and are ready to go. Then you take a 2-5% cut of that (just a hair more than credit card transactions) for the online business referral.
TL;DR- Give business owners something expensive and massively valuable in return for their data, and the ability to let consumers buy their items through your referral system online.