Looking at Google, Nextag, etc.. it appears the JBL can be found in the lower 200's upto the mid $300 range, lower than the smallest Axiom.
Heath, the subs job is to primarily play the LFE's in movies and accompany your mains for music on frequencies below whatever crossover setting you have set on your receiver. Most decent subs will fill that need. I can't comment on the quality of the JBL sub, never owned that brand. I can say the Axiom speakers are excellant.