While some may think it is not expensive , most of us wouldn't spend 1 btc on this . I think that in the long term you would benefit more if you implement some kind of mining fee (reasonable % of coins going to you) into software and give it for free.
With a single rig of four R9 270, you can get 40 XPM per day, you will make your investment back in a week.
If you what you're selling is actually true....