ok, my advice...get the M60's and then get a sub used on ebay. subs are not as important on make as the fronts are for timber to the center. since you have the VP150, and i know from personal experience the m60's have loads of bass when needed, i'd say get a new sub after...and you can get great deals online used. just my thoughts

Axiom M60Ti Infinity 2000.6 x 4 Infinity RS1 rear Infinity CC200 HSU VTF3 - MKII