This organization seems to have the least expensive test kits for formaldehyde. Most kits are $100, but this one is $50 (click on the post title for the link). Maybe the others send pros out to do it; this one is do-it-yourself.
Also at that site are mold test kits for $40 and radon kits for $10.
We were supposed to go out for a belated Valentine's Day dinner next week. I wonder if I can persuade "teh huzzband" that a test kit is the gift I really want...
The "we could be famous" blog has the goods on toxic FEMA trailers.