$400 would hurt for a road car, but if you have the cash, why not? Pedders charge me $140, tyre shops $70ish.
Just a theory, but because Pedders test drive it, unlike the rest I've been to, they'd really have to price for the possibility of alignment, test, re-tweak, test. Just the initial drive to say all good, wheel at 12 o'clock is worth the extra cash for me. The car handles noticeably better aswell, not sure about tyre longevity yet.
In summary, if possible get alignments done somewhere it's test driven and even more importantly, never assume a suspension/tyre shop won't either wash, or have washed by a third party, as in my case, your pride and joy.
F**k me, the "by hand" car wash they used to clean my "washed yesterday" paint, probably by a couple of Ford loving 18yo's, mauled the paintwork. I don't know the business, but I swear they must have used the wheel water from a 4wd with a broom!
I had spent some cash on other things, so it was obviously an ass kissing that left me with a painful bite!
If you give anyone your keys for so much as an inspection of something, you might feel stupid checking first, but as they say about assumption...