Filter #2 was custom-made. Not sure if that's orderable in small quantities outside of academia. But you could try to find a filter that fit their "naive approach", which would be simple bandstop (aka "reject" or "notch") filter that blocks approx 450-510nm. Just looking around the same retailer, maybe something between these two ([2] & [3]) might suffice for experimenting? Ideally it would fit that range precisely AND have a rather absolute cutoff. I have no idea if that kind of arbitrary range selection is available to one-off buyers, I'm just a fan of color theory. :P
The issue with the naive approach is that it skews the white balance of the results a bit by affecting the M&L cone stimulus as well, but that's a lesser issue for playing around with the idea.
[1] - http://www.omegafilters.com/450lp-rapidedge.html
[2] - http://www.omegafilters.com/products/filters/500rb.html
[3] - http://www.omegafilters.com/products/filters/460-od-0-4-notc...