I got an ad from MCM for these this morning, http://www.mcmelectronics.com/manufacturer/EXCELITAS-TECH/01000312 (http://www.mcmelectronics.com/manufacturer/EXCELITAS-TECH/01000312). Since they are made by the same place that makes the vactrols, I thought they might be OK. Price is pretty good if they are good.
6k to 200k is pretty limited range.
The applicability for your application is based on the range of the LDR so you'll need to check that to know if it'll work for you
The quality is somewhat irrelevant without the requisite scope of control the part would offer.
Just FYI, Excelitas bought PerkinElmer's production of vactrols and LDRs.
you'll need to check the specs of whatever you're building, but in most cases you'll be looking at the "light" and "dark" specs, which are often something like 10K/ 10M +
so far, I think Smallbear and Allied are the best sources I've seen.
I was mainly wondering about the noise level with these. I've played with a bunch of LDR's and Vactrols. The only types I've really been happy with are the VTL5Cx types. Everything else has been noisy or muffled or crappy some other way. I guess for the price I can just put a couple in the order the next time I need something from MCM. But, that's not really very often. I really should check the spec sheets to see how fast they are and what their memory is like too, but I can probably come up with some way to use them if they sound good.
A definite +1 on Allied as a source for the Vactrols. They have the best prices I've seen on them for quite a while.