Acceptable for you maybe, but my 50 texts a month costing me $7.50 +tax (15 cents per txt) would be a scam, thankfully I had the my fives thing where I could send free texts and call, for free, 5 people for an extra $15 per month, considering you can pay 15, or 20 cents for sending "Ok" to someone while using less than 10 bytes of bandwidth which flows with the signal the cell has with the tower already anyways.
Now I have a pay as you go cell for I use it to little to warrent paying $55 a month, they got plans for pay as you go's now, I can pay 30 cents a day to have 10 texts daily or 50 cents a day for 100 texts daily, thats 0.5 cents per text, so if they can afford that for a mere pay as you go client, then yes 15+ cents per text is a rip. The biggest BS is paying to receive texts though, thats 30+ cents per text lol