It's definitely worth it. You can write off a portion of it for business. If you shop around, the plans can be fairly cheap. I pay $122 (including taxes/fees) for five phones (two are smart phones) through Tmobile. I have unlimited minutes, text, and data although I think I got grandfathered into some special plan as a long term customer. I write off one phone 100% for my tutoring business. I write off 50% on another for my mystery shopping business.
On a side note, I wouldn't get a smart phone simply because a company is trying to force you to check in via the phone. I am a hold out on that and refuse to do it.