Looks like the seller recently dropped the price to a more reasonable level of $750. My only possible "red flag" is the amount of components replaced in a recent "shop checkup."
https://reverb.com/item/95312347-alembic-f-1x-preamp-freshly-serviced?bk=eyJhbGciOiJIUzI1NiJ9.eyJqdGkiOiJhN2Y3OWNlNi1lYjRlLTQ5YzEtODZjZC0wMGY2M2NiMjBiMTAiLCJpYXQiOjE3Nzc3NDA3NTcsInVzZXJfaWQiOiIyMjM5OTQ4Iiwic2Vzc2lvbl9pZCI6Ijc4OTRhN2Y3LTAyN2QtNDU1Ny1iZDQwLTRhNjQ1NjRmMjVmYiIsImNvb2tpZV9pZCI6ImQ0ZGRkOTllLWMxMzAtNDA0ZS1hZGQxLTEzNDk0OWYxYmNiMiIsInByb2R1Y3RfaWQiOiI5NTMxMjM0NyIsInNvdXJjZSI6Ik5PTkUifQ.5jQO4YyjEecrhxRyjzitgTQIY1PoCoeuzurX11z2zLM