The auction's listed with free shipping. So it's $50 a machine shipped. It probably costs the seller $18-$30 per machine for shipping (depending on how far away the buyer is and how well the seller packs everything).
So considering you're paying $20-32 per machine net, I think it's a very nice deal. Certainly you could obtain some of those machines locally for free or very little money - but it would take you a long time, most of them would not be as good a condition as this auctions' ones are, and it would also likely require a lot of driving around (time+gas money).
Worst case scenario, you pay $399 now, sell 2, 3, 4 or 5 of the eight machines in a few years when their value increases, and you still have at least a few left for a net price of zero, or even a profit.