The only problem I have with the Red Book is that they give very pessimistic values. The market value of my car according to the RACV is a massive 50 to 100% greater than the redbook prices. The Trading Post prices are more 'real-world', and likely to be somewhere in between those extremes.
Red Book is great for comparative purposes and general information, however.
Jack Travis, E-Series Acting President
1989 Ford Fairmont Ghia turbo/GL replica (underway)
1994 Eunos 800M
1990 Ford Laser S