You run into some issues with using SLI on an AMD rig because it has to have an nVidia chipset in order to SLI(2 cards at once)
Just looking at your list I'd bump every item against newegg.com. I understand that tax can be a pain, but when you're getting a 22x DVD-RW drive for 30 bucks, when you can get the same from newegg for 20-22 the tax isn't really going to matter. More importantly, most of the time you can combo newegg and save the equivalent of tax+some. As seen in batuchka's build. Combo combo combo.
If u already had a HD 4870 then a 2nd one if u could nab it cheap makes sense but hitting 2 x HD 4870s for CF now would be inefficient as the HD 5K series are way more better in that dept.and in any case i suggest a single beefy GPUs olution actually ^^