New, the dCS Scarlatti DAC was a roughly €22,000–€24,000-class component, depending on exchange rate and market; at €10,900 used, this example is clearly ambitious. Your four comparables put the median at €5,317, with the 75th percentile at €6,869, so the asking price is nearly double the median and leaves little room for negotiation or future resale.
That said, the Scarlatti remains a serious, beautifully engineered digital hub: its Ring DAC, extensive AES/SDIF/SPDIF connectivity, balanced outputs, selectable filters, digital volume control, and master-clock capability make it unusually flexible in a legacy high-end system. It is a satisfying choice for someone specifically building around the Scarlatti ecosystem, but at this price the unit should be exceptionally complete and demonstrably serviced, with remote, original accessories, and flawless operation. Otherwise, the market evidence points toward waiting for a much lower-priced example.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.