Monitor 70 and 30's or 60's and 40's

[BLindsay]

Basically i have enough to get the following

Monitor 70 fronts and monitor 30 rears

Monitor 60 fronts and monitor 40 rears

Center will be CS2 either way


newegg has the 70's for $400 for pair shipped, and the 30's for $100 shipped
amazon has the 60''s for $300 for pair shipped, and the 40;s for $190 shipped

unless i can find a good deal on both then i can either do one of those options, only have about $600 to work with for the speakers (sub and reciever are seperate) (reciever is more than likely going to be the onkyo 606 which on that i wonder if going from the monitor 60s to the 70's is worth it? also is there really any good reason to get the 40's over the 30's for the rears?)