Before you buy old school title, check it

The Underdogs were my first abondonware site few years back :) I stopped using it while owner (woman i think which amused me back then) had some problems with domain and updates were freezed for a long time.

As far as i'm concerned it's non profit organisation which tries to archive internet sites, books etc. to save them from oblivion.

I don't think they would do that illegally

For first 70 years after publishing (according to law in my country - in some it is 50 years, in some 99. 70 is most common one as far as I know) you can't copy, distribute or share software in any way without copyright holder permission (in simpler words - abandonware is software published before 1945, or the one which copyright holder decided to abandon his rights by publishing it under fully free license) Selling or not selling software got nothing to do with this.

But Archive.org got permission to publish free of charge, on-line only, unmodified versions of some games on their website. I know that they tried to get permissions for few other games, but they failed to secure publishing rights. Which makes this website 100% legal.