How much would it cost to re-host all these sites? If you hosted a snapshot it'd be completely static, a small cluster of Varnish servers would be trivial to set up and could take quite a beating (alternately you could leverage a CDN I guess? I don't know much about such things). Either way I doubt it'd be a huge investment to keep them online as static, archive sites (which is a very different commitment to keeping them actually live, which would obviously incur many more costs).
I'd not expect any of these sites to be heavily trafficed going forward, so my guess: $5/month.
Note that large portions of geocities are being hosted on the web by various parties, most of whom are apparently using pizza money to do it. Geocities was still in the top-100 websites or so when it closed, and they're probably getting decent amounts of traffic from people trying to find old sites.
Even if there is heavy traffic, you're hosting a archival copy, not a production site, so you can just degrade performance as needed. See often slooow web.archive.org :)
Completely agree. I think there'd be an initial spike, but anything after that would well be within the capacity of my server, which is ~£30 a month. Not a high price for preserving the information... but how long would I want to keep it online, especially once it was only seeing a handful of hits a day.
