| Date | Region | Description | Price | Seller |
|---|---|---|---|---|
| Switzerland | Formant Filter bank with 4 analog bandpass filters. Opt... | $301.38 | ||
| USA | The Rare Waves Grendel Formant Filter v2.0 (after ... | $180.00 | ||
| Switzerland | The overall condition of this *Rare Waves Grendel Forma... | CHF250.00 | MDLMusic |