Well, I will be offloading my own STRDG820 shortly...bought it a little while ago on sale for $300 from FS on a oneday sale. I'll be posting the review soon too...need to snap some more pics.
IN regards to speakers, I always suggest people do not get a speaker with a port facing towards the listener. Such speakers are using the port to fill out hte speakers sound, but bass is much better when re-directed off of a wall...other than that, the more you spend, generally, the better the speaker. So get the best you can within your budget...because I cannot make any recommendations without a budget!
In regards to subs, check FS in person ask see if they have any Athena products still in stock(not listed on site any more), the sub should be very decently priced(P4100), and works a treat...I use two of them myself.