It's a little confusing. But the Mark II bass sports the Guild humbucker pickups.
They sound fine and some players swear by them.
But the M-85 basses that commanded those high prices were the earlier models
Equipped with the Bisonic pickups. Awesome sounding basses.
Post 2009 the prices paid for those dropped to around $2500,but I am basing that on one auction and a fleeting offer by someone who quickly thought better of it.
As noted above, the seller will be lucky to get $1500.