My friend works at one of the big 4 accounting firms doing international tax, and $5k is the going rate for the services he provides. He said most of the time their services are paid by the employers, though they have a few high net worth individuals who pay for the service.
Ah yeah if it's a big service like that, esp. selling via employers, I could see $5k being the going rate. My employer paid for Deloitte to provide relocation assistance (mostly helping me find an apartment), and I think they charged about the same. You don't really get in the door at those kinds of places for less than a few $k.
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.
