Tough choice.
Do the CLA and you are set for the next 10+ years.
Get one from KEH and in a few months it may have a problem where it needs a CLA, or it may go for 10 years w/o a problem. You don't know the history of their used gear, and neither do they.

BTW, I'm not sure if you meant buy a NEW body or a used body from KEH. I know KEH from their used gear, I did not know they sold NEW stuff.

Yeah I agree with you, getting your entire kit serviced is goina be EXPENSIVE. Personally I would hold off on servicing until you have a problem with a specific piece of gear, unless you're a pro, then you need to do preventive maintenance so it won't fail during a job.
Have you checked Flutot's, they are down in Southern Calif. http://flutotscamerarepair.com/
You can also call International Camera Technicians in Mountain View, up in the SF Bay Area. His prices are similar to David's, but he isn't a Hasselblad specialist like David. He's an older guy, so best to call him on the phone 650-961-5825.

Number your backs, so you can keep track of them. Then if you have problems with a specific back you can ID that back and just send that one in.

I'm also in the same situation about servicing my gear.
Since I'm not making money off my gear (as in being a pro photog), I'm taking the wait and see approach, vs. preventive maintenance.