This looks like a fair-to-good ask, not a bargain. At €3,700, it sits below the more common recent used listings I found for a Klimax DS/3, which cluster around roughly €4,400 to €5,200 on the lower end, with many examples much higher; so the price is competitive, but not so low that it screams steal.
That makes it a sensible buy if the unit is truly excellent, complete, and fully functioning. The DS/3 is well-regarded for refined streaming performance, Linn ecosystem integration, and a genuinely high-end presentation that still holds up well; if it’s a clean, original-owner piece with box, remote, and power supply all present, the value is stronger still. I’d only press on condition, firmware/service history, and included accessories if anything is missing, because those are the details that separate a good used Linn from a merely cheap one.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.