Those appear to me to be the last (5th) version of the ESS AMT Monitor from what I can see, but the serial numbers will tell more.
All but the first version have cone passives, they are the same cone and casting as the woofers but without the magnet assembly. The cones are Bextrene (mineral-filled plastic) with a urethene-rubber surround, which on mine had lost some of their elasticity and needed replacement years ago (can't say for all, but I'd expect them to be stiff, maybe even brittle by now if exposed to enough heat and/or UV light as all older rubber and foam degrades). Note the black Heil, also an indicator of later versions, and the closed sides in the tweeter portion of the cabinet, all earlier versions have cutouts in both sides with a grille/screen insert. They also have the late-change to the tilted Heil.
From the photos, it looks like the Heil diaphragm pictured is original and in good condition, all parts intact other than the aftermarket grille material and some veneer damage on the cabinets. I don't see the ESS emblems on the grilles, those will cost money, new surrounds x4 will cost money (and very difficult as the rubber will need to be carefully cut away from fragile Bextrene cones), new grille fabric, some veneer/cabinet repair, and of course they are un-tested. Also check that the grille frames are not broken as they often are.
Were it me, I have two pair and know what they are so I might pay up for another pair of late Monitors like these, I'd be willing to go as high as $750.maybe more. I would use the reconditioning arguements in the above paragraph, the ugly fabric, and the fact that they're nearly 150# each in a world where people are buying small HT and stand-mount speakers (at least as far as an auction employee is concerned). I know I like them and the late version is what I want to start with. If you're not sure whether you want them and especially if you need to send speakers out for repair etc., you might not want them unless under $500. The obliterated serial number (unless it's just the photo) would cause me to ask the auction staff if they were stolen, another reason to lower the asking price. Also check the built-on black base, it was a late change from the solid base to a particle-board riser/base with four feet and wasn't IMO sturdy enough to hold up to decades of moving these heavy beasts around, it might be gone or damaged or at least missing the four corner-mounted feet. Another deduct.
There are no sold examples that I found in a quick search, only a pair with a $1,500 asking on ebay so it's hard to get a current value. Those on ebay are the early foam passives but are otherwise apparently in good condition, but again that's an asking price only. I do feel that a good pair in excellent condition is worth $1,500, and all parts and service are currently available from ESS, but that isn't an auction price unless you really want a pair. The lack of knowledge of the brand (
www.esslabs.com I believe ) make them a bit harder to sell and keep prices down, ... if they said JBL on them they would certainly sell for triple what they bring.
Best of luck. These were the best IMO of the series, built with better drivers and crossovers than the Rock Monitors and sold for more, personal preference here toward a good 2-way but I'm pretty sure you've read the many arguments over which is better. The ability to completely eliminate the crossover on these via rear-panel jumpers and biamp is just frosting on the cake.
. Sell It Again Sams did the sale. Great people. Helped me load them.
And yes they do make it complicated.
