And if you don't follow the letter - well, depends how much the IRS thinks they can extract from you.
Considering my taxes would be easy peasy, I wouldn't think $5k is out of the range of normal.
If you're an individual with a fairly "normal" expat job (just a salary), I'd recommend finding an independent tax preparer who's done expat taxes before. There are a lot of CPAs who have 1-person offices doing tax prep, and some are knowledgeable about how to file for an expat. I asked around and found a friend-of-a-friend in that line of business.
I've been very happy with their service and am happy to recommend them.
I've filed a total of zero tax forms with the UK government in my lifetime. I've filed several hundred with the US government in a couple of years (and paid third parties money to file "for me" because filing directly is insanely difficult).
That said, there shouldn't be; there's quite a bit of lobbying by the aforementioned tax prep industry to prevent simplification of taxes to the point where everyone could simply file them on their own, as well as to prevent the establishment of an online government-hosted tax prep system. And that's completely ridiculous. The IRS already has more than enough information to simply send everyone a pre-calculated bill.
The IRS says the average time to complete a tax return is 13 hours: - 12% complete 1040EZ at 4 hours each, - 19% complete 1040A at 7 hours each, - 69% complete 1040 at 16 hours each [1].
Since some 150 million returns will be filed this year [2], that's an aggregate of almost 2 billion hours spent. That's just federal, of course. States are probably less time each, since they piggyback on federal, but there's certainly some time spent there.
[1] http://www.irs.gov/instructions/i1040/ar03.html [2] http://www.irs.gov/pub/irs-soi/P6187.pdf