Dear Severus and Victor,
These coins are indeed rare. I have collected them and images of them for some thirty years, and this is all that I have found: 8 officina A (including five in museum collections), and 10 officina B (including two in museum collections).
Early this year a paper by me was published in Numismatic Chronicle, where I discuss these coins. My conclusion was that the coins struck for Crispus were actively withdrawn when he fell from grace. Anyway, it’s all in the paper.
So Severus, you have a rare coin, with only three officina A on the market (known to me). You have one, I have one, and the third was sold by orgame on eBay 10 May 2012 (to Zenon M). Officina B is a bit more frequent, and a new specimen appeared this April on eBay, very poor, but I bought it. Your example is an obverse die match to the coin in Milan (Sabetta 195) and a reverse die match to the one in the Hunterian (published by Robertson).
As we all know, the value of these LRBs is usually determined by condition, not rarity. So although the Crispus coins from Constantinople are excessively rare, they usually don’t fetch more than other coins.
And Victor, many thanks for all the work you put into this forum. I and many others appreciate it!
/Lars