Landscapes

I am getting close to completing my collection of landscape plate blocks. Of the 171 plate blocks listed in Bale, I am missing only 6. 2 of these 6 are well out of my reach (LS6 at $2000, and LS113a at $3000). The remaining 4 (LS7, 27, 51 and 55), should be within my budget, assuming I ever see them for sale. LS55, which catalogs for $8, is the one that doesn't really fit here. LS7 and 51 both list for $280, and LS27 at $110, so these are evidently more rare. I don't think the catalog values are very accurate, since I never came close to paying full catalog price for any of the more valuable blocks (I think I averaged paying less than 20% of catalog price), but they should be useful to reflect relative scarcity. That is why I am baffled that I am missing one that lists for $8. It should be relatively common. Of course, the common ones were where I actually had to pay much closer to actual catalog price (sometimes over it, when you factor in shipping). Dealers seem much more willing to get $30 for a $110 item, then they are to get $5 for a $10 item. It seems counter-intuitive.
Shouldn't the rarer items go for a higher percentage of list price then the more common items? My best guess is that there just aren't that many buyers for this type of material now, and dealers are just trying to clear their inventory before the catalog makers catch up with the new reality of the market. Will this ever happen?