If that sub is new, there is no manufacturer warranty to go with it since you bought it on eBay.
There is a user on this board called Mr Marv that builds awesome custom enclosures. PM him for more information. This is his website:
http://community-2.webtv.net/MarvsPlace/MarvsPlace/
The least expensive way to stop the woofers from producing bass that the sub would produce would be to get some things call bass stoppers. These go for about $3/ea on partsexpress.com. They also have crossovers that will high pass but those are at least $25 ea. Whether you go with bass stoppers or crossovers, you will need one for each speaker. As for preventing the sub from producing trebles, you just set the crossover on the amp accordingly.
