If they can't find one then they may pull up eBay and see what Antminer S9's most recently sold for and give you cash value(which won't be much as in 3 years
You never know... I picked up a couple s5's for like $500 a couple months ago (little less). I did so knowing I was paying too much and likely would be better off spending the money on coins, but I could double my money if I sold them now. They are 3 year old machines and are selling for the INSANE price of like $600 a piece right now...
eBay prices are known to be extremely inflated (you can find obsolete miners for even a third of eBay prices or less commonly on the forum), and thats not always true. When the price of BTC falls and mining becomes less profitable like it was in 2015, miner prices also tend to fall. The price varies quite a lot. S5s sold for near the $100 to $150 dollar range even a couple months ago, and they recently shot up just because of the recent crypto hype. You cant count on that.