The used RTX 3090 is no longer ~$550-650 - it moved to ~$900-1,000 in Oct-2026 and escalated to a $1,430-2,220 asking band on the Dec-2026 refresh

Any cost model or buying decision predicated on a ~$550-650 used 3090 is now wrong by ~2-3x. The Oct-2026 realistic band was ~$900-1,000; the Dec-2026 refresh observed asking prices of $1,430-2,220 - a further +50-130% spike.

Used-market repricing compounding. Hardware Corner's tracker measured used 3090s at $750 Nov-2025 rising to ~$950 by Feb-2026 (+27% in 3 months); the Dec-2026 PicClick-mirror refresh then captured a $1,430-2,220 asking band, inflated by 2026 DRAM+AI demand.

At $1,430-2,220 asking the used 3090 is NO LONGER the default budget pick it was at ~$950 - cross-shop a used 3090 Ti, 4090, or a bigger-VRAM datacenter pull instead. Always re-verify eBay completed sales (not just asks) at purchase time; asking and realised prices diverge widely on inflated SKUs. Re-run multi-GPU math at the new band before assuming a 4x rig is still the cheapest 70B path.

The value edge eroded and then broke. At the Oct band (~$950) nothing at 24GB undercut the 3090 on speed+stack maturity; at the Dec-observed $1,430-2,220 band the budget case is gone - a 3090 Ti (~+9% TG) trades in the same range and a used 4090 or a multi-card B70/MI100 build should be cross-shopped. See supply/ebay-used-rtx3090-dec-refresh for the new band.