subwoofer for music?

Hi all

My Speakers are the neat ultimatum mf5 which claims to have specs of

MF5 response @ +/-3dB is 28Hz - 40kHz. The typical - 6dB point in the bass is 22Hz. (from BOB of neat)

Can a 6.5" driver get that low?? Proacs and PMC also have specs that go that low! While speakers with drivers of 12" only gets to 30+hz usually...not sure why

I dont feel a lack of bass from the speakers, but having a sub that can fulfil both role of music/movies and help my system to get down to 20hz will be awesome! (will set the crossover at 35hz or less)

However i will have a subwoofer regardless because i will use it for theater, and the pv1d just does not cut it for movies. So therefore im looking for a sub to be used for music and movies with budget as low as possible.

Will 2 subs help stereo imaging? I would much prefer a single sub for convenience .
Room is 8m(6m usable) x4m. So after reading some info, here are some choices that is within my budget (but i would prefer to spend as little as possible)

-jl audio f113

-twin velodyne spl 1000 ultra

-jl audio f112

-bower wilkin db1

-velodyne dd15 (not plus version)

-twin jl audio f110

-mk 350 mk2

-rel r528

I heard about SVS and KK and paradigm subs, but they are a pain to get in my country

Any help will be appreciated. Thanks all :)
Why is SVS a pain in your country? SVS only does mail order! What country are you from?
REL is outstanding for music. I used Velodyne also but it was not suitable for music, it's hardness was tiring.
REL & JL are the two best in my humble opinion. They're both "fast"--i.e. they can be set to be in near perfect phase with the speaker, they are both very musical, and they both go down to the bottom. Here's where they differ: The JL offers way more meat & body, and REL subs are more resolute with less body. If you listen to bass heavy music than JL is absolutely the way to go. If you listen to music without any extreme emphasis bellow 100hz, then you can consider a REl sub as well. Personally I prefer JL over REL
"REL are very cheaply made"

JK, can you expound on that?

Which others are made well and how?