Yea it could be expensive. You can find something around a river or lake and boil it. Just post pictures of it before hand so we can see if it will work or not. In time you'll get it together. I think it looks a lot better with the background.
You did a great job!
"When creating an aqua scape, strive for the beauty of imperfection, as its art and there is no wrong or right, it's left open for interpretation" James Findley