i took the plunge and made a bass drum subkick this past weekend. it wasn't that hard to do.

$10 8" fisher brand woofer from a local audio repair shop
1 $8 hosa 2' xlr cable (i couldn't stand to cut the end off a long one i had)
a $22 hosa in line pad (set to -30 db) highly recommended
scrap 2x2's and plywood from the garage
black paint

voila, $40 later, a kick boootay subkick heh

i'm using a 14x22 8 ply rogers maple bass drum
clear ps3 batter head w/ impact patch, 1 ply clear front
medium muffling (towel)
pearl eliminator quad beater (soft plastic side)
audix d6 and sub into m-audio octane preamp, protools 6.4 le
there's a bit of eq and compression on the d6, no eq and some compression on the sub

hope this helps

van