I just did a short search and I did not see any Bilsteins that were over $200 each for trucks and vans.
Some start at $60 each so $400 each is really high even if thats the installed price.
They are not that hard to install so two hours for all four should be about the time a shop would charge.
I did a set of four in my driveway in about an hour and a half.
Quigley vans tend to ride a bit hard in the front and shocks can only help so much, don't expect it to ride like a car on bumps with just new shocks. I am not sure what you have now or how many miles you have on the current shocks, but you could always do just the front shocks to save some money.
You might need to do some research about the part numbers for the Quigley as the are not going to be a standard size. Also there are a few different models of Bilsteins as well some will do more than others it depends on your needs.
http://www.performance4trucks.com/parts ... hocks.aspx
I too would strongly suggest calling Chris at U Joint Off Road, he can help you get a good price and the right shocks as well.