I was wondering the same thing not long ago, and the answer is actually no. In general terms, SMS marketing is one of the least expensive marketing venues out there. That’s because even if the rate for SMS messages is high in your phone plan, you can get a business plan that makes each SMS much cheaper. Managing the campaign is also inexpensive, and you can even find a free text messaging service for business if you look around a bit.
The biggest hurdle in SMS marketing isn’t the cost of the campaign. It’s collecting enough phone numbers to make the campaign worth the effort and coming up with the right content and marketing strategy to get a good conversion rate out of the campaign.
These are not trivial problems, but they are also the same hurdles one needs to overcome when putting together an email marketing campaign. So if you already have one of those going, you will have no issues expanding into SMS marketing.