e.g. 10 years ago people were dumping CRT monitors, now a decent Sony Trinitron starts at 150-200 €
The SGI machines are difficult to get hold of in the UK to begin with plus they are as other said short supply. There is one Octane in the country and it is the machine only (even though the monitor and keyboard are pictured) and it is going for about £800 on ebay.
If it was everything I would have said "that probably the best deal I am going to get" and went for it.
In those days I got an extremely cheap Sun workstation on ebay as an example.
Anyway, I guess supply is low but there are still nerdy people who think an old Unix machine is cool. (I'd take one running Irix just to play with for sure.)
I bought my Octane on eBay in 2008 (it was previously used at Ford), I think it was around $80 and shipping was more than half of that (an Octane weighs ~80 lbs).
Here's a crazy one I saw yesterday: the Canadian government auctioning an unused Origin 3400, still in shipping crate. https://www.gcsurplus.ca/mn-eng.cfm?snc=wfsav&sc=enc-bid&scn...
I would love to own an Onyx, even just to look at the case. Just because of what it represented for me as a kid who could barely afford a Voodoo card.