X/O for subwoofer

I have a peerless 12' 830500 .I am looking at using one of these for power Behringer Reference Amplifier A500

my question is what is the best way to add the X/O into the equation withoutit costing an arm& leg

. maybe one of thesehttp://www.jaycar.com.au/productView.asp?ID=KC5452&CATID=25&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=557

or is they a better way

one of our local suppliers sell these

SUBWOOFER X-OVER ACTIVE
Stereo 12dB Low-pass
active filter. Compact
design for adapting a
subwoofer to your system.
Adjustable output levels
80/125/250Hz LP switch
S/N=100dB THD=0.02%
Base 65x90(x28H)mm

But i suspect it not great at $ 14.50 trade I can't get a link to work thanks