Hey guys. I'm a senior in high school and my senior project is coming up. It determines if I pass or fail high school. Anyways, what I'm doing is I'm gonna buy a subwoofer, a prefab box, and then I'm mentoring a guy to build a custom ported box. Then I'm gonna get a meter and play different frequencies and compare how loud it is from Xhz to Yhz(not sure of exact frequencies yet) then I'm gonna make a line graph that compares the two and how they perform with different frequencies. If anyone could help with a cheap sub that'd be awesome. Thanks.