I just finished upgrading my home theater, also now 5.1.2, and spent almost the same amount for everything. Hehe. I-share ko na lang yung ginawa ko at yung na-research ko, baka makatulong. Disclaimer lang, I'm also quite new to this whole hobby, so take my advice with a grain of salt.
For the speakers, you might want to check out Anthony Audio Speakers while his high-end Titus speakers are still available and on sale (until end of August na lang). You can find the store on Facebook, and you can check out the A-Audio thread here (
http://www.pinoydvd.com/index.php/topic,70456.0.html) for customer feedback. I find the Titus speakers perfect for movies and music.
For Atmos speakers, from my research, mas recommended either ceiling speakers or speakers mounted near the ceiling, rather than the upfiring speakers. I also found that Atmos speakers are generally pretty light on the specs, so I decided to just use a couple of the old Onkyo HTiB speakers that I have, which I mounted near the ceiling. Convincing naman ang Atmos effects.
For the receiver, my research led me to either Denon or Marantz, since they have the highly-praised Audyssey room correction software. I ended up with a Marantz SR5010, since it has a good power supply (650w), Audyssey MultiEQ XT, and I got a good deal on eBay--open box for ~$500 (my receiver and subwoofer were from the US, I just had them shipped by sea through LBC Shipping Cart). Other models I considered were the Denon X2200 and X3200, which have been on sale lately sa Amazon for ~$500 due to the release of newer Denon models. Audyssey cleaned up some of the bass issues I have in my room, and also allowed my cheap Atmos speakers to integrate well with my other speakers.
For the subwoofer, I was considering SVS, Hsu, or Rythmik. I decided to buy the Rythmik L12 (~$540) due to the servo technology, the sub-20Hz extension, and the relatively compact size. I'm very happy with the Rythmik: bass is clean, powerful, and accurate; and they're very honest with their specs, kasi ramdam talaga yung mga sub-20Hz frequencies. And I think the servo technology helped minimize some of the bass peaks and nulls in my room.