Lets do this.
A good listing of accommodations in the area:
There are only 2 "official" campgrounds in the area, both are pretty much booked up the next few weekends, with a few first-come-first served sites. The sites look pretty much booty. We can camp anywhere in the forest, but we would take some exploration to find a spot (mebbe a recon day trip?). There are a lot of campgrounds along the White Pass area, but getting to Crystal would mean paying for entry to the Mt. Rainier Natl Park (or driving around the mountain).
There is a campground at the NE base of Mt. Rainier, first-come-first-served, but park rangers there are hardcore.
In my personal opinion our best bets are gonna be (in no order):
1) Grab one of the last sites (prolly crappy ones) at a developed campground.
2) Find our own camp site.
3) Either the lodge or a chalet ($120-$200) a night