It may not be possible to buy 108,000 of these products. 108,000 of them may not even exist.
That is correct. IIRC Amazon has only ~10K of those GPU instances. Also Amazon puts limits on the number of instances one person can purchase. It isn't completely anonymous (they don't want the bad press of say Iran finally perfect nuclear detonation timing using EC2 instances). After the Sony hack, in which the attackers used Amazon instances, there is a lot more cross checking of instances. Large number of similar instances run by "different users" is very likely going to get audited/halted.
If you need 100 nodes EC2 is viable. If you need 1,000 nodes you might be able to get away with it if very clever (multiple identities, careful IP proxying, camouflaged instances, etc). More than that EC2 is a dead end.