Ethereum Classic has been a pretty dead chain to date, with no (or very few ) decentralized applications, no cross-chain tokens, and very little development. It was created after a big Ethereum hack was reverted (back when Ethereum was in a similar state), out of a mix of idealogical and opportunistic principles.
I meant it in the sense that ETH Classic (the "brand" if you will) was created at that point
Is it really a better deal than selling the graphics cards?
Though it remains to be seen if the Eth Classic price will hold up with a lot of new, constant, sell pressure from miners. If the influx of miners greatly outnumbers other users, the price will likely go into a dive, until miners no longer can mine ETH classic profitably.
Then, it's likely many (the ones who don't care to speculate on future price appreciation) will either try to find a different chain to mine for, sell their cards, or store them for a point where the tide price/hashrate shifts to make mining worthwhile again
I for one would not touch a secondhand card from random ebay seller. Those cards were running non-stop and probably have limited lifetime in them anyway.