Note I am in NZ, so I'm using pricespy.co.nz for prices, some products may not be available (or as cost effective) here.
Some things I was considering:
Case: Corsair Carbide 200R for ~$98 or Antec One for ~$85?
CPU: Is the i5 3570 worth an extra $20 than the 3470? ($290 vs $270). I don't think I will be overclocking so I haven't opted for the K.
Motherboard: The B75 won't overclock but I don't see that as a problem. Should I be switching the B75 for an H77 or Z77 for any reason? The AsRock B75 Pro3M is $105, to get an H77 or Z77 it looks like it would bump the price up to $150 - I can't see much benefit?
Should I be getting a less powerful GPU? The 7850 seems pretty powerful, but at $319 I don't know if it's worth it over my other option lower was the HD 7770 for $175
It seems my build would need ~350W according to some calculators. Is my 550W overkill?
I am considering tossing the Blu Ray drive and maybe installing it later to save some cash up front.
The build overall looks pretty good. Don't worry about your PSU, it gives you some room to spare but that's not a bad thing.
The difference between the B75 and H77 chipsets are minimal. B75 doesn't support RAM overclocking, doesn't have Intel Smart Response Technology, and doesn't support RAID configurations, so I'd probably recommend the H77 just because it gives you a little bit more flexibility. Neither supports CPU overclocking but since you don't plan on it then that's not a big deal.