how old is too old when buying speakers?

The age in years should not be the most important issue. Depends on how the owner treated them, what kind of music he preferred to listen too (as a link to the average volume, I mean). I would not suggest buying speakers without an audition. If you can arrange this then go ahead. My AudiogoN experiences are just wonderful with just one exception and in that case a laywer friend made sure I had the check within 3 days :-)
Merry x-mas!

Speakers are not like fine wine, or Stradavari. 5 years, however, is a short time in the life of speakers. However, and that's a big however, you read it above: how have they been treated in those 5 years? You have to trust the person you're buying from. No 'gon resume, forgeddabout it.

I just recently bought some Tukans used. Great speakers for the cost! Could use a sub though. Anyhow, in terms of upgrades, I spoke with Linn and the only upgrade has been the protective cover on the tweeter. They told me that this was purely aesthetic.

Aside from abuse, THE part of concern is/are the capacitors in the crosover. They, reportedly, have a ten year life.
Peace-on-Earth

Trust your instincts...if it seems too good to be true...or u sense the seller maybe playin' ya...pass...there are too many reliable folk on Audiogon...always check feedback,call seller,have pics emailed,etc...this doesnt guaranteee a smooth transaction...but it sure helps...just for the record...I tend to go with dealers over individuals...also...in a small room the Tukans would be fine...