Yeah there's a guy on my local CL who's had a natural/maple T-40 up there as far as I can recall since the beginning of the year. $600. Has never price dropped once. Just re-ups it a couple times a week to bring it to the top.
I do dig T-40s, but for $600 I would probably get some kind of CV Squier or put another hunnerd or two with it and get a used Fender.
I keep seeing Natural finishes go for like $500-$550 in average to good condition. Seems crazy to me but I guess it's not crazy, they've just become much more desirable.
I rescind my original comment, I feel they are a great bass and definitely worth that $500+ price tag...but it's hard for me to swallow because just a few years ago you saw them all the time around $150-300.
