Please don't be heartbroken! I promise you everything is going to be ok!
It's perfectly normal for baby snakes to be nervous and strikey. They're not all that way, but it's not uncommon. To them, everything in the world is a gigantic predator. It takes time for them to learn (in their very slow way) that he/she is safe in their new home.
It's very likely that when they were at the pet store, they were kept in less-than-optimnum conditions and were too cool. A cold snake is a calm snake because they just don't have the energy to be defensive. Also, it may have been used to the environment at the pet store, as hectic as it was....and moving to a new home has freaked it out a bit. Just give it time to adjust.
A full week in its new home at least.....without any intrusion from you except to make sure the water is clean and fresh. That should help a lot. Then very gradually begin to handle the snake, just a few times a week, and only very briefly until it's quite used to your presence and realizes you're not going to eat it.
Have a look at our caresheet for some excellent suggestions on setting him up in a perfect home:
http://www.ball-pythons.net/modules/...warticle&id=59
Good luck with him!!