BBM uses a miniscule amount of data... as long as you're only sending text messages through it, it won't cost you much - if you start sending pictures or videos to each other, it will start to cost you.
Beware though - some of the big companies have been known to charge up to $50/MB in the US - you really shouldn't be paying more than $10/MB without a special package, and if your provider offers a US Data Saver option ($10 for the month, then $1/MB), i would strongly recommend you use one.
If you want to communicate with people who have iPhones or Android phones in a similar fashion, you can download an app called WhatsApp... it's very similar to BBM, uses slightly more data, but can still be significantly cheaper than texting.
I'm on WIND Mobile, and they charge $4/MB in the United States (without any special roaming plan)... very reasonable if all you're doing is BBM/WhatsApp/Email.
Beware though - some of the big companies have been known to charge up to $50/MB in the US - you really shouldn't be paying more than $10/MB without a special package, and if your provider offers a US Data Saver option ($10 for the month, then $1/MB), i would strongly recommend you use one.
If you want to communicate with people who have iPhones or Android phones in a similar fashion, you can download an app called WhatsApp... it's very similar to BBM, uses slightly more data, but can still be significantly cheaper than texting.
I'm on WIND Mobile, and they charge $4/MB in the United States (without any special roaming plan)... very reasonable if all you're doing is BBM/WhatsApp/Email.