Benq 1640, 1650, 1620 are to recommend, can be found at Ebay. But you never knew in which condition are these old drives. IMHO these are the ultimate drives for CD-scans, also because it can scan more than C1 and C2
P-CAV is correct, but Z-CLV-scans I´m not sure. However, P-CAV is great and fast, much better than 8x CAV of the competitors.
Other good CD-scanners like LiteOn CD-RW are more rare, Plextor also and mostly very expensive. I don´t used Plextor often for scans because it is very slow and and I don´t like the graphs of Plextor-Software
I´m not sure about Panasonic-drives, my newest is made in 2013, maybe Panasonic don´t próduce it anymore?
QSI maybe also stopped production, Original QSI-drives are not to found in Germany, the Pioneer-QSI-drives getting rare, my DVR-221 is produced in 2014.