I figure to do all four corners, it's probably going to be close to $500. The Blazer is probably worth maybe $2500 tops in good working order. It's got about 150,000 miles on it. Amazingly, the body and interior are in great shape. No rust, dents, dings, tears, etc. It's just the undercarriage that is rusting.
Oh, well in that case it's not so bad. Probably not a fun time, but sounds worth it.