Dahlquist DQ-1W subwoofers-value??

Just curious if anyone would give a ballpark for some good to excellent condition Dahlquist DQ-1W bass modules w/o cross-over.
I checked on the Audiogon blue book but it is not there. My gut tells me a good condition should be about $200-$400 depending on condition. That is of course a 2X spread but hopefully a start.