Why don't you make your own rock use cement and crushed coral.
You will need it to neutralize but it won't take a lot off cash just time.
You should be able to get that cheap or almost free if you ask on the board.
If you ask people might give you some leftovers as far as plumbing etc just to get rid of it as we all know you are 13 and your funds would be limited.
Not the cheapest hobby to go into.:wink:
I might have a few things left over after I finish setting up my tank.

yep i'll be looking around for free and cheap stuff. once i get a job i won't be that limited. i know it's not that cheap but it will be fufilling when it's done. it will cost alot more because i have a 50g Fw tank and will make it into a 60g Fw planted tank before i set up the Sw tank.