Here's eBay history on that seller -- about 500 chips sold over the last 90 days. Almost all of them are Horseshoe chips & other items from various time periods.

Lots more have been sold in earlier months, though eBay Search function doesn't go back further than 3 months.

https://www.ebay.com/sch/i.html?_nkw=&_sacat=0&LH_Complete=1&_udlo=&_udhi=&_samilow=&_samihi=&_sadis=15&_stpos=81301&_fss=1&_fsradio=%26LH_SpecificSeller%3D1&_saslop=1&_sasl=business101101&_sop=12&_fosrp=1&_dmd=2&_pgn=3&_skc=384&rt=nc

As Michael mentioned, this hoard is being sold by a relative (nephew? though not sure) in the Binion family. When supply exceeds demand, prior valuations collapse. (On the other hand, it's an opportunity to pick up some previously pricy chips at good prices! And a few Horseshoe chips are still scarce.)