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My 24' Argosy is a '75. At the price level you're quoting, I'd expect ALL systems to work correctly, all glass windows (i.e. no plexiglass or acrylic unless it's a Minuet), tires with a few years of life left in them and a reasonably solid floor with a usable interior. In short, a trailer you could hitch up and go camping in without too much work. It's not likely to be cosmetically perfect, but it shouldn't be ugly. After that, it's a question of what you think it's worth to you as long as you're looking at it as something to own and love and travel with. If you're thinking about using it a season and reselling, I suspect the $10k is way too high.
Condition, condition, condition. Inspect carefully, look for dry seals, signs of leaks, soft/rotted subfloor, signs of regular use and maintenance, etc.
Il Carriaggio — 1975 Argosy 24 | Il Progetto — 1976 Argosy 28 Center Bath | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill