I have an Ooma VOIP phone at home costing $7.40CAD a month, which is cheap.
I saw this Slytext plan and bought initially the cheapest tier and wrote them to set up my SMS using my existing phone number. I wrote into tech support at support@slytext.com.
Beth answered but had problems figuring out my carrier. They were closed on the weekend, but this morning I got an email saying everything is hooked up! It works, I wrote my parents and got replies and now writing customers as well. Since I'm saving so much on the phone, I bought the highest tier, so that should more than cover my needs.

I'm an incredibly happy Slytext customer, thanks Appsumo for bringing this to market on a Lifetime deal!