I've got a handful I scored but they are super hard to find in good condition and usually very expensive. $50-$100 is about what I see them go for usually.
some of the explosion proof ones I have use big sodium or some other bulbs with a larger than normal screw base, so I converted them to standard 300 watt 120v receptacles by spot welding the new ones in the old cage. if yours are like that, they are easier to sell if they take normal bulbs.
Mogul to medium base adapters are not hard to find.
What’s so special about these?
$1750 ouch, will check them out Friday, has a 100 ton press for $200 also.