Arrgh, I just wrote a long reply which is now gone, gone! (wails)
Thanks for all the super-helpful and detailed replies! The initial excitement of moving had died down, but you guys have got me all hyped for it again 
I will have medical insurance (that provided by the grad school), but I think it leaves the door open for some pretty non-negligible bills: $200 deductible, 20% co-insurance, $2,000 out-of-pocket maximum, 40% prescription co-insurance (no maximum). These figures are for in-network (bc+bs blue options) - roughly double costs for out-of-network.
I’m assuming there’s no roadblocks to me getting my warfarin on the WalMart $4 prescription drugs programme. I’ll be on warfarin (or another anticoagulant) with blood tests for life, and it’s a relatively cheap drug, so that’s ok. In England, I’d get the tests free, of course, but prescriptions are £7 ($14) per month per drug (all prescriptions are free here in Wales, where my parents live) - so even including blood tests, the difference is manageable.
The real decider will be my other drugs I think. I take a beta blocker ($27 according to the bc+bs site) and an ACE inhibitor ($61!). Different doctors have given me conflicting information on whether I’m on these long term or just whilst my heart recovers from the surgery - aortic valve replacement - I had in April.
I’ll also need to see a cardiologist at least once per year, and get the standard tests (echo, ecg, chest x-ray). I’m assuming this will be in the hundreds of dollars, even after insurance.
Wow, just writing this is making me want to seek out the cheapest place I can find! I think if I budget $100 per month for medical costs, that should be somewhere on target.
Still, my health won’t be all bad for my expenses - it limits me to 2 or (at a push) 3 drinks in one session, and to be honest I prefer not to push it. My hard-drinking days are behind me (legal age here is 18, and I really put some back when I was an undergrad - college bar was 200 feet from my room, and oh so subsdised cheap!)
On the air conditioning, I’m with you. I lived in an initially non-aircon apartment in Fukui (about 3 hours north of Osaka) in 2005-6. Japanese apartments are stereotypically insanely poorly constructed and insulated, and that was certainly true in my case. I arrived July 31, and Fukui is noticeable hotter and more humid than Tokyo. I tell you, that month I prayed for a swift death as I tried to sleep with 3 puny fans pointing at me every night.
I should have been clearer - the housing quotes I had were for a room in a shared house, hence my lowball estimate on utilities.
I have found another apartment listing on craigslist, which I am seriously considering. It’s in a place called ‘Glen Lennox apartments’ (zip code 27517), near campus in Chapel Hill itself. Walking distance to campus, though as I understand it campus is so large that I shouldn’t put too much faith in this. Only 200 yds from the bus stop though. I noticed some negative reviews on the Web, but they seem to largely refer to the age of some of the places, and this one has been recently refurbished.
The rent is $323 per person, and I’d be sharing with 2 other people. My share of utilities is estimated at $50. The main drawback seems to be that it’s small, and perhaps away from the funkier areas of Carrboro and Franklin st (?). Still, a girl who lives there now is staying for next year, and she’s a UNC student - so it can’t be that bad!
I’m not too bothered by the size of the apartment - my other options of where to go were central LA and New York - my money would certainly have stretched a lot less far in either of those places!
I can’t tell you how excited I am to be moving to Chapel Hill and the US in general. Almost all my friends, including the hardcore America-bashers (the ones who steer an innocent conversation with a friendly American tourist into “so… who did you vote for?”) are revealingly and satisfyingly jealous that I’m getting to live there for awhile. And not to be morbid, but there’s a non-negligible chance that this bum ticker of mine will kill me at some point in the next few decades, so I’d like to see as much of the world as possible. A few thousand $ in medical bills pver 5 years seems like a fair price to pay!
My main whinge is that on my stipend I might (will!) struggle to see the places in North America that appeal to me, off the top of my head: Boston, Niagara Falls, Vancouver, Canadian North-West, Seattle, Vegas, San Francisco, Death Valley, Monument Valley, Grand Canyon, Tijuana, D.C., Colorado mountains.
Again, huge thanks for all the tips,
zhongguorenmin