I got this massive (8" x 10 1/2" x 5 3/4" thick) 3-volume series, The Oxford Dictionary of Byzantium inexpensively. A casual glance through it shows a bit of everything. Want to know what a "mappa" is? It's in there. Want to know about the title "Clarissimus"? It's in there. I imagine much of it is now on Wikipedia, but probably with less authority. Anyway, I love books. Here is a Byzantine coin: Justinian. 527-565. 10-nummia piece (see the X in exergue). 21-19 mm. 5.91 grams. VICTORIA AG One of the very few AE Byzantine types with a reverse legend. Sear Byz 271. MIBE (Hahn) 220 "struck 547-552"
Not sure what your idea of inexpensive is but bookfinder.com has lots of them with the cheapest being $137.