I've been using the re:Match plug-in for similar tasks with success. It costs $90 but there is a demo version you can try out:
and also a tutorial from Andrew Devin:
You can also match footage in Speedgrade, but I haven't tried that feature yet.
I've tried RE:Match, and it gives good results. I'll try Speedgrade too.
Is there any other plugin (preferably free) that can do the trick? RE:Match is focused on taking the whole clip as a source to correct the color, and I'd prefer to do it as "OK, change this color to that other one I pick, and then apply the change values to all of it". That way the results would be nicer.
One could probably rig some effects with a sampleImage() expression, but color math is not trivial, especially when it needs to provide a perceptionally consistent result. Anyway, without seeing the footage it will be hard to advise specifically, but your workflow sounds upside down. The common approach with all color correction is to create a neutral setup first, meaning you try to correct both clips so their colors meet somewhere in the middle and only then you tweak the colors to create the specific grading. Your current procedures are bound to fail the moment you add more clips and your meticulously tweaked footage looks out of place again...
I've tried it, but I can't get it to work. I'm using the 3.0.7 version.
I import the clip I want to the change, then I open the gallery and try to open the clip I want it to change to, but it says that its format can't be supported (even though they're both AVI).
I've tested it the other way round, just to see how it worked (importing the "reference" clip as "source" and the "source" as "reference"), and I was able to import the reference to the gallery, but whenever I try to play the reference clip in the left window, the controls actually act on the right window (the source clip) and the left one remains black.