Anything is worth whatever someone is willing to pay.   Why would someone pay $500+ for an SSK that comes with the styrofoam package and the cardboard box??   There are users and then there are collectors.   Industrial SSKs sell for $1K+   Why??   I have no idea. 
I will say that my initial batch of SSKs cost me about $40/ea.   5 of them.   Packed and shipped so horribly that one was destroyed.   Luckily, the other 4 arrived intact.   
Over the years, I've paid as much as $600 for a certain model and as little as $120.    They were ALL worth the money I spent, so I'm perfectly happy with it.   
This is GH, where we pay $200+ for a small plastic toy cap, but we'll scrap around to save $10 on an entire keyboard LOLOL.   For me, the SSKs that are earlier with the one-piece caps are worth a HUGE premium since I personally prefer the over the two piece variants.    And a properly set up SSK is as nice a keyboard experience as my $500+ Korean customs and far more enjoyable (for me) than Topre which unfortunately all of my friends LOVE. 
The SSK from cpbuen was a great deal and I'm surprised it sat there so long unsold!!   If I didn't have so many already, I would have had one of my friends in the SF area grab it for me.  
And yes, a Bolt and LED fully restored Maxx board is priceless imho.   Worth EVERY penny he asks for them!!   My 2c for the 1c that it's worth     
 