Don't know if there's a 3rd party app for it, but I suggest you get a look at Tasker's capabilities. You can do A LOT with it after you have an understanding how it works.
Sent from my GT-I9100 using xda app-developers app
[EDIT] Hmmh, it seems the task you have described in OP couldn't be done in Tasker either..There's an option for that kind of behaviour, but ONLY when done by Tasker i.e. SMS sent automatically by Tasker. So if you want automated texts, yeah sure, but not the way you want it unfortunately. At least not directly, need to think of a convenient way to make it work..