There are a couple of things about collecting Byzantine coins if that is what you want to do.
One is that certain coin issues are quite common, both the gold and the bronze, though not the silver. One would find it easy to collect the coins of a dozen or so emperors from common mints. It could be a nice-looking collection if you bought quality. But all the rest of the 69 “names” on coins (including the anonymous issues) listed in Sear range from scarce to impossible.
Byzantine historical characters are mostly obscure. You mention Roman Emperors like Augustus, Caligula or Hadrian at a cocktail party, your partner in conversation will likely have heard of them. But who was Basil II? Andronicus I? Maybe they’ll have heard of Justinian I. That’s probably it for Byzantine Emperors in the normal awareness of our era. A millennium of history, “our” (Western, I guess) heritage, we think about it hardly at all.
Another is that the export of all of them is prohibited by the Turkish government, in whose territory most of them were made. This has pretty much shut down the export of those things by mail from Turkey, though stuff continually finds its way out of the country, too much for any customs agency to care about. But the coins circulated,
