First of all, I'd like to know if you will be going active. If you are getting a DSP, I will be assuming that you will be (not too many people install a DSP and go passive). And, if you go active it would be a waste of money to buy a component system for the front stage. You would get a much better "bang-for-the-buck" if you got raw drivers from Parts Express or Madisound. With component systems, you are purchasing crossovers that you will never use...if going active. I am not very familiar with raw drivers as I am still running passive (not for too much longer, hopefully), so I will not be offering advice as to which drivers to get. There are many here who can, although...and probably will.
If going passive, I use Morel's Tempo Ultra 602 two-way components. They are considerably less expensive than your $650 budget, but I absolutely love them. I can play them loud all day long without getting ear fatigue and without any ear ringing when I turn them off after extended periods of loud playing. Impressive bass response, as well, as long as you deaden the doors. You should very definitely do that.
I looked at some pics of the 2010 Honda Odyssey and it does not look like you will be able to put in an aftermarket head unit. It looks like you will be stuck using the stock head unit. If I am correct here, then you will almost be forced to get a DSP if you are wanting the best possible sound from the sound system. That previously mentioned Helix P Six DSP looks interesting. If you want to go to a separate, outboard DSP then the Helix DSP.2 or the Mosconi 6to8 Aerospace are probably two of the better DSPs on the market.
For the 6-channel amp, the Zapco Z150.6 LX would be my choice (if not opting for the Helix P Six DSP). Get the LX version if going the Zapco Z series, especially if you are getting the outboard DSP. My second choice would any of the other Z series Zapco 6-channel amps. Third choice would be the Arc Audio XDi 1200.6.
Now, if you are looking for an SQ 8" sub, I'd recommend either Image Dynamics IDQ8 or Dayton Audio HO 8". There are lots to choose from in this category.
Remember, these are just ideas, recommendations, things to consider. But, should give you a good starting point.