The finish of the Ti books appears to wear off, especially on the metal frame around the keyboard area.
Generally they are older.
I think that as long as you can live with the optical wear the sweetest used Poerbook deal is one of the first DVI models, with 667 or 800 MHz with 1 MB cache, 15" widescreen, Radeon 7500, gigabit ethernet, wireless slot. They can be had for $700 for the 667 model. if you want widescreen in a Al Powerbook you pay very big bucks.