Budget musical sub: sealed or vented design....

REL Strata III...if that's no enough bass for you, buy two of them and run them as a stereo pair.

I realise apt living is not ideal for an audiophile...but hey...what are u gonna do?...at any rate...consenus is front firing is better suited?

People have stated that Parts Express has some great DIY subs.You could save some $$ that way.There are other DIY sites which give some designs(listed below for starters).

I am going to take that route(DIY)and try to get the XO point to tightly match my Main speakers insteas of getting the regular Variable Setting amp types.I would like to get a REL ,but thehy are expensive.I like their Philos. though.

I do not know weather it would help,but you might try to elevate the sub and place a Granite Slab at the bass to isolate it from the floor which might make it alittle easier on the neighbors below.

You might want to check some of these DIY sites!Just the info alone can guide you for other things!

http://www.diysubwoofers.org/talkshop/
http://home.earthlink.net/~etunstal/diy.htm
http://ldsg.snippets.org/index.php3
http://www.audiodiycentral.com/