I As of Feb 2010 the labor cost was $100.00 per hour for items not under warranty.
I'm not sure how long it would take to replace both covers, but with the cost of parts and estimating about two hours of labor, it would be around $742.00, maybe a bit higher. So it looks like you were real close Nick. ;D
Of course, if I were doing it, it would probably take me all night.
Just dumb luck on my part!
The other possible "wild card" in this repair estimate would be if Apple charged more or significantly more for the parts vs. iFixit.
Slightly off topic...but relating to the quality of the repairs at an Apple Store. I bought a Macbook last week which still had warranty left on it...and got the display bezel & the upper case replaced (the part with the keyboard, palm rest, trackpad, etc.)...these are the items that most often suffer from the case cracking that Apple has agreed to replace. Both the replacement display bezel & the upper case were not installed properly.
To add to this...I purchased an iMac G5 a few weeks ago from a guy who's computer was suffering from kernel panics/freezing. He took it to the Apple Store, they replaced the ram, and the kernel panics continued. He decided he was tired of the problems, and I purchased it...assuming that it could be a "doorstop"!
Turns out the Apple Store installed the wrong ram. It was ram from Crucial...and Crucial confirmed it was the wrong ram (based on the part number on the ram).
So what I'm saying is (at least when it comes to my local Apple Store)...the repair quality (for the high prices you pay)...may not be the best. I'm sure many many folks have had positive repair results...just a little weird that I've run into a couple "duds".
- Nick
p.s. The repairs the OP needs would probably take me all night as well. Since I would be SUPER DUPER slow & careful...especially if there are a lot of screws to keep track of. And of course the first time you do a repair always takes longer...the 2nd time around you can probably do it in like half the time or faster.