Locent (YC S15) Lets Businesses Sell Products via Text Message
techcrunch.com
techcrunch.com
[1] just one example I found via a quick search http://goqr.me/qr-codes/type-qr-sms.html
Do you plan to work on distribution, or only on connecting buyers and sellers? I can almost see, for example, having a local clothing store list each of their shirts with your service. Then someone sees a shirt they want, text, and get it delivered.
Best of luck!
SMS was invented in 1992, and definitely popular by 2000.