Reverse SMS chat sales work better.
The model is easy, plenty doing it.
You need a multi-number sms bridge service (there's plenty of them)
Then you want a bank of 5 - 10 numbers on the bridge service.
Then you post ads on Craigslist or some other classifieds site (locanto is the one to use in AU), place it in the personal services section with a mobile number. What section and what ad wording you use depends on the niche.
Then you simply wait for people to sms you. If you use a simple API driven front end you can handle a dozen or so numbers on the one display. Because people are sending you messages it doesn't matter if you go to sleep or walk the dog or whatever because you can reply any time. You could have 5 to 10 on the go at the same time and use manual selling. It also doesn't break spamming laws because you didn't initiate the sms conversation
A bit of creativity gets people to your link and those that become a pain in the arse just block them.
Then rinse and repeat. Recycle to new numbers and go again.