You have to understand to get good stuff you are gonna have to spend money. Thats just the way it is. Save up untill you can afford better quailty stuff. Just because it looks like an l7 doesn't mean youll get the same performance. 400 isn't much to spend on a "good" set of subs and a good amp. You can do that ebay stuff but imo its crap and not worth the money. Youll end up with a boomy system that truely sounds like crap cause your highs wilo crap out soon or youll get the ear bleeding highs that some people seem to love...

if you want bass look at something like this

http://cgi.ebay.com/ws/eBayISAPI.dll...category=18797
or even
http://cgi.ebay.com/ws/eBayISAPI.dll...category=18797

Then look at a set of subs that can actually take that much power. Then do us all a favor and get an amp for the highs.