Why... "personalised"? Forget all those messages with the same text for everyone and with no valid sender's number. Your SMS messages will look and feel like you dedicated time to compose each one of them, since they may contain personal information of each recipient.
Why... "automatically"? You can create a new task in less than 1 minute. You select the recipients, write the message and transfer the task to you mobile phone. During task execution you will able to see a full report regarding the status of each message in your task.
Why... "inexpensive"? You don't need to sign-up for any service and you don't have to buy message packages bigger than your real needs. You are completely independent, since the whole process is executed by your mobile phone, with all the benefits this comes with. Most of the times, mobile connection providers offer a number of free SMS messages each month (e.g. 1500), which are wasted because not used. Using them you could literally eliminate the whole cost of your messages.