The Spring King is a real spring reverb pedal from Danelectro and while it’s not the only one it is the most affordable. Or at least, it was; I haven’t been able to confirm it yet with Danelectro, but it might be discontinued.
It has disappeared from Thomann and Sweatwater lists it as no longer available. One other site I looked at actually did use the “D” word but most others just list it as out of stock, as does Amazon. It could just be a supply chain thing but none of their other inventory seems affected so. . .
If you think you want one it might be worthwhile to look around some of your local shops or favorite websites to see if they have any stock left.
Mine should be here next week. 
These are very mod-friendly pedals too from adding larger spring tanks for a longer, lusher reverb to activating the pedal’s unused digital delay. I like the idea of using a bigger spring tank and putting it into an amp shell with a remote switch, sort of a solid-state version of the old Fender tube-driven reverb units.
