How many SMS messages can I send? Is there a limit?

You can send an unlimited number of SMS messages using the SMS Blaster. However, in some cases, your phone provider may impose restrictions, especially if you've never sent bulk messages before or if you're on a prepaid plan. If your messages are blocked or limited, it's often due to your carrier's policies. In such instances, a quick call to your provider explaining that you intend to send a higher volume of messages can usually resolve the issue.

As for costs, using Pushbullet, you can send up to 100 messages per month on their free plan. If you need to send more, you'll need a Pushbullet Pro account. More details are available here: Pushbullet Pro.