It all depends. I have seen a bunch sell over the years and the range has gone from around $600 to somewhere around $1100. It seems like there are a lot of factors that go into determining price. If it has a hard case, that is a plus. The wood upgrades also seem to add to the value (the Alembic webpage lists some of the upgrade costs, if I remember correctly). Condition also matters. I would guess that you would need to deduct a bit for the missing knob and maybe for the ding, depending on how big it is (the ding that is). You see a lot more Spoilers for sale, which is a very similar instrument (I think there was a somewhat recent post by Mica that said it was the same body and neck and just different electronics - soapbars which were an upgrade at the time).
Do a web search and you will probably find some Persuaders or at least some spoilers for sale. And remember to deduct a bit from any prices you see from dealers, who are going to get more than a private seller (like buying a used car in my opinion). Hope this helps.
p.s., I just noticed that you posted a question about this bass a while back (called it a distillate at that time - I assume it is the same instrument). I would guess that you need to make this clear to a buyer and maybe expect to get a bit less if the seller is worried about future problems.
