If you are looking for a cheap background do what I do and use tinfoil. This looks great comes in different colors and even paternes now. I don't like to fight with triing to keep it all looking flat all the time so I crumple it slightly for a totaly different look. 1 rool of tinfoil will cover a few large or a lot of small tanks. I think it looks better then store bot backings and if kept smoth it will give a mirror like effect. Not realy a DIY but I felt this was best searved in this section.