The site is quite hard to navigate, since it lists all the parts. (Basically they have a prefix before the item for you to know what kind of part it is eg. atx = case, vga = video card, etc.) I was confused the first time too lol.
Sadly, the memory is not available here, same with the motherboard. Ill definitely keep your build in mind though. Things arent that much more expensive here, maybe $5 more or so.
Find any memory that is 1.5V, DDR3-1600, CL9, and preferably has low-profile heat spreaders.
If you have spare money, try getting a 3570K and something like a Z77-Extreme4 (not Extreme4-M), GA-Z77X-D3H, or P8Z77-V LK. Those will let you OC the CPU and run SLI/CrossFire. Should cost about $150 extra.
You could also get about a 600W PSU from Corsair, Antec, Enermax, PCP&C, SeaSonic, OCZ, or XFX. Drop down to a 7870 if necessary; there isn't a massive performance difference.
How will this build do? Will it play BF3 on Ultra?
CPU: i5 3450
Motherboard: Asrock Z77 Pro 3
Video Card: Asus HD7950 DirectCUII TOP 3GB/384-bit
Memory: G.Skill Ares 4GBx2 1600 (is this memory good?)
Storage: Western Digital Caviar Blue 500Gb (already have)
Storage: Crucial M4 128GB SSD (will this perform similarly to the Samsung you suggested? Samsung isnt available here too )
Power Supply: Seasonic M12II 620W
Case: Corsair 300R (will this case have enough space for the build?)
Memory great; would have been second choice after the mushkin and only because of about $1 of price. M4 is fine though not quite as fast. 300R is big enough. As you can't SLI and CF is crippled you could get the 520w version of that PSU. Should play BF3 on ultra @1080p. Will look at benchmarks. (Graphics card is one of the best 7950s out there FYI)
EDIT: From the 660Ti launch review two months ago, so fairly recent drivers: